As Muslim, sex life is affected by the following two things:

  1. Five times of daily prayers 
  2. Ritual full body washing after sex

Both of them work in "combination" with each other and affect sexual life. 

The biggest relief that I got after leaving Islam, was to get rid of hardship of 5 times of daily prayers. Islamic prayer is like a "responsibility" which occupies your mind. And till the time you don't fulfil this responsibility, you will not get relaxed and you will be unable to concentrate on other things in life (either it is studying, or working or simply enjoying life).

Muslims claim that feel calm and relaxed after offering prayer. But they are mistaken and they don't realize that actually prayer is like a burden/responsibility, and of course when they are finished with prayers, then they feel a sense of relaxation. Therefore, this burden/tension in their mind was itself caused by prayer. Without the responsibility of offering prayers, they are automatically free of tension and automatically relaxed. 

As far as "full body washing" after sex is concerned, then Muhammad took this practice from the Jews (link), just like he took many more practices from Jews too. 

Note:

There is a difference between "wadhu" and "full body washing". 
For prayers, normally you have to do "wadhu" (i.e. washing your face, hands and feet). 
But if you engage in sex, then you enter in the state of severe impurity, and you are not allowed to pray in this state. In order to become pure again, it is obligatory to take "full body washing".  

Their "combination" works like this:

1. Five times of daily prayers.

2. Once you get discharged, then Islam tells you that you have entered in a state of severe "impurity".

3. In this state, you could neither pray, nor touch Quran, nor enter in the mosque.

4. Not only is your soul impure, but your body and clothes and bed sheets and blankets all become impure and you have to wash them too. The sperm and female sexual discharges are the most disgusting things in the minds of religious Muslims (just like urine and feces). 

Therefore, if you get the wish to make love, then:

1. Still you get the mental tension to calculate the prayer timings first, if they are colliding with your love time or not. 

2. You will get the tension to calculate not only the prayer timings, but you have to first plan the "Bathing Time" too prior to the prayer. 

3. If it is winter, then you have to additionally calculate the time for making water warm too.

4. Women with long hairs specially have nightmares from this full body bath, while they have to wash their hairs too every time they make sex with their partners. You could think yourself how miserable the life of such women becomes due to these Islamic rulings. 

5. Sometimes, you also get the tension of clothes, which you want to wear after making love and taking bath. Sometimes you have to plan to iron them too before indulging in love making, while after that you have to immediately go to the mosques for the congregational prayer. 

Short breaks between Noon/Afternoon/Evening/Night Prayers:

Another problem is this that the time breaks between noon/afternoon/evening/night prayers are very short. If you get the wish to make love during this time (noon till evening), then you are almost always under other tensions of prayer timings and bathing and clothes too. 

For many people, sexual SATISFACTION does not come with one time ejaculation. But this satisfaction comes from the whole process of love making, which normally looks like this one: 

1. Time for foreplay

2. For most men first time ejaculation is a matter for few seconds to few minutes only. 

3. Enjoying from taking rest or sleeping naked with wife for some time. Specially women want to stay in the arms of their partners as sign of love. 

4. And then get ready for the 2nd round of love, which lasts longer than the first round and it is mostly there that one gets sexual SATISFACTION. And if you are young, then you may often want to go for the multiple additional rounds of love too.  

Morning Prayer:

The biggest injustice has been done with the "morning sex". For many men, the morning sex is the greatest blessing. 

In summer season, time of prayer comes even before one wake up naturally after taking full sleep. Therefore, he has to make his wish to make love to sleep again, but he himself has to get up and leave the bed for prayer. 

After offering morning prayer in the mosque, it is difficult that wish for love arises again, while firstly there is a tension of getting late for office, and secondly you have to take the time for taking bath too (otherwise you could not offer noon prayer at the work while you are in state of impurity).

Especially in winter, it is extremely difficult to take a bath with cold water (otherwise one has to invest a lot of time in making water warm before taking a bath). 

Morning sex is especially a nightmare for the working women. And it becomes even more difficult for them if they have long hair. It is unimaginable that such working women could voluntarily take a bath in winter morning, and then go to their offices. It is a recipe for getting sick. 

Night Prayer:

You have enough time to make love after the night prayer though.

But still, it is not completely free of problems. Many men are not so much sexually active in the night to go through whole love cycle. Many men want one round of love at night, and then 2nd round in the morning, but this is difficult to achieve as Muslim, while you and your wife have the tension to take full body bath at night too, otherwise they have to take bath with cold water early in the morning before the Fajr (i.e. morning prayer). 

Weekend Sex:

According to one friend, his wife extremely discourages sex during whole week, but she is ready to make love at the weekends, when she puts half a liter of coconut oil on her head hairs, and then say to him:

In English:  "Listen Darling, if you wish (to make love) then come now, otherwise I am going to take a bath in half an hour. "

(Note: My friend and his wife are originally from Indian Subcontinent. It is common there that women give massage to their hairs with lot of oil in order to make their hairs thicker and beautiful. Nevertheless, for their partners, usage of so much hair oil is a killer for their wish to make love)

And once she has taken a bath, then she puts the notice of "No Entry" on the board. 

I also encountered days when I came home, full of sweat, then took a bath in the afternoon/evening. After taking bath, I felt myself fresh and got the wish to make love. But then I sent curse upon my wish, while I knew that it was impossible to take the 2nd bath within one hour time. 

And wife also looked more charming and attractive after she had taken the bath and made her hair beautiful. But I had no courage to ask her for love making, while I knew that it would be painful for her to go again to the bathroom after one hour, and take a shower and dry her long hair again. I was not an animal, and I was able to understand her feelings too. Thus, I had to strangle my wish of love. This is not a JOKE, but a bitter truth and reality. 

Lesson:

It is good to take a bath after sex, but if your partner has taken a bath and made herself neat and clean before the sex, then certainly it is more important than taking a bath afterwards.  

Note:

Actually, it is not only the sex, but also the "nightfall" which brings you in the state of severe impurity according to Islam. And young boys normally have no courage to ask their mothers to make them water warm during the night or early in the morning before the morning prayer. 

Actually, everyone came to know about the "nightfall" if I tried to take a bath before the morning prayer. Therefore, I went to the bathroom secretly even before the morning prayer, and took a bath with cold water. Still my family came to know about my nightfall as the bathroom was wet due to the bath. 

Masturbation brings you into a state of impurity too, and you need to take whole body bath. Perhaps 99% Muslim indulge in the practice of masturbation too, despite it's been not allowed. 

Religious Taboos don't let you satisfy your wife:

I doubt that, as a religious person, you are in a position to take much care of the needs and satisfaction of your wife. 

Sex is considered something dirty by the religious people. 

Oral sex is strongly discouraged as male and female discharges are considered impurities. 

They don't talk openly about sex with their partners and consider it somewhat against the "modesty". 

Islam asks you to think about Allah even on the bed with your wife and recite a DUA before starting sex process. This causes the diversion of your concentration. 

Conclusion:

It could be said with certainty that a lot of changes took place in the sex life after becoming irreligious. New horizons were discovered in the sex life, which were unknown to me as a religious person. A tension free and relaxed mind could enjoy sex much better. 

Islam apologists: But Prophet Muhammad used to easily have sex with all his wives in one night

Answer:

The era of Muhammad was different than our era.

He didn't have to go to the office early in the morning. Actually, he absolutely didn't have to go to the work and had whole day free to make sex and take bath.

And people used to go to bed very early in that era (just after the Isha prayer, which is about 6 pm to 7 pm (depending on the season and the area). Thus, they were able to have enough time to sleep till morning prayer. 

But this is not the case today. Working hours are long, and people go to bed at about 10 pm, or later. They don't get enough sleep if they make love after 10 pm, and then again have to get up early in the morning for prayer/sex (or for both).

And Muhammad took bath early in the morning. But if all his 9 wives also took bath early in the morning without making any complaints? ... I don't know, but surely normal women today find it really difficult to take bath so early in the morning (especially in winter while then they also have to make water warm).

Islam Apologists: No need to change the clothes as 'Aisha used to scrap the semen from garments with her nails

According to Islam, both semen and the female liquid discharges are "severe" impurities (just like urine and feces) and one could not offer prayer in such clothes. 

Therefore, if the clothes get the semen (or female liquid discharges) then I could only tell that personally it became impossible to use those clothes any more as every Muslim feel "disgust" from them, while they are big impurities. 

There are 2 ways of making those clothes pure again:

  1. The first one is to wash them in water.
  2. And another one is to make them free of (dry) semen by removing it with nails (like Aisha did). 

I tried several times to make the clothes free of dry semen with my nails, but not a single time I got success in it. It is almost impossible to achieve this task. I wonder how 'Aisha was able to remove it with her nails. 

Ultimately, clothes were unusable for me after that, and I had to wash them with water. 

PS:

I wonder how Muhammad asked 'Aisha to do it for him (i.e. to scratch his semen from his garments).

I personally never got the courage to ask my wife for this service.

Actually, I would not allow her to do this even if she is ready to do it. Reason is simple that semen is so disgusting as Muslim that it was difficult for me to even touch my own semen on my clothes. I was compelled to do it for the first time when I had no other clothes and water, and I had to offer the prayer at the right time. Thus, I tried to remove the semen with my nails, but failed miserably.