Why You Should Not Have Sex with a Cheating Husband
Many women believe that having sex with their separated husbands will keep them faithful or make them want to reconcile. Nothing could be further from the truth.

Men and women are not the same. If a man is having sex with his separated wife, that is an indicator that their relationship is doing pretty well. The same cannot be said for a woman who is having sex with her separated husband.
For men, sex is often an indicator of achievement rather than relationship. Biologically, they are driven to have sex with as many women as possible. Having sex with one woman does not remove the desire to have sex with another. For these reasons, men often: 1) stop putting more effort into a relationship with a woman they are having sex with; 2) continue to desire other women, even when they have a healthy sexual relationship with their partner; and 3) can have multiple sexual relationships while still professing to love one woman. If you are having sex with your separated husband, you are taking away from any motivation he may have to recommit to you.
Separation is not a needs issue

Men and women separate for different reasons. Many women don’t know this and so believe that their husbands separated because their needs were not being met. This is one of the most common myths perpetuated by psychology. Even men whose needs are completely met by their wives have affairs.
If you want to know how to get your husband back, it is important to understand why men leave. All they need to have is the opportunity as well as a lack of fear of losing their wives if they do. So, husbands of needy wives are far more likely to cheat on them than husbands of secure wives.
Secure women will not put up with such unfaithfulness; insecure (needy) women will. Of course, if you have treated him very badly, then he is also not likely to fear losing you, no matter how secure you are.
Meeting his needs is not a solution
Because men don’t leave because of unfulfilled needs, attempting to fulfill his needs after he leaves will do nothing to motivate him to come back to you. He will of course enjoy anything you are doing for him while separated, but that won’t make him think, “Now my wife is really fulfilling my needs. I guess I will go back with her.” Instead, he will enjoy his relationship with you while also continuing to enjoy his single lifestyle–having his cake and eating it, too.
He must lose something from you if he is ever to miss you
Men leave in search of something better. If they find it, they are not likely to come back, no matter what you do. However, most of the time, the grass is not all that greener. Even the beautiful young woman he got involved with dumps him. There is a reason that married people want to be single and single people want to be married. Your husband experiencing that will help to move him back toward your marriage. But, if you help him to have the best of both worlds while separated, then he won’t want to have either–he will want to have both. By having sex with him, you will endorse his lifestyle. The longer this goes on, the less inclined he will ever be to be monogamous again. Even if he lives with you again, he will continue to cheat on you in the future.
Dissatisfaction is the key to reconciling
If you have done a good job of maintaining boundaries, while also keeping a good connection with your estranged husband, then he will be drawn back toward you. Those boundaries have prevented him from being able to have his cake and eat it, too. He has missed out on family life with you, having a shared home, having family vacations, having the security of someone to wake up with each day. He has had to be financially responsible to any children you have and has had to single parent for a part of every week. He is likely to find that he has given up more than he is getting.
Take him back slowly
In his dissatisfaction, he will attempt to romantically reconnect with you while still being connected with others. This you must not do or you will take away his motivation to connect more with you. However, you can encourage him to stop contact with other women so that he can start dating you. You need to have some conditions for taking a cheating spouse back to prevent repeat cheating. It will have to go slow and sex won’t re-enter the picture until he has once again earned your trust (not just promised to be faithful) and worked consistently to build your relationship over a period of at least three months while still being separated. The number one mistake that women make is to take their husbands back before love, trust, and commitment have been restored. This results in stagnation, distancing, and repeat affairs.

Let him know your back-up plan
Nothing helps a man to stay on the straight and narrow like knowing the consequences of what will happen if he doesn’t. This is what keeps faithful men faithful. In your process of rebuilding with your husband, it would be wise to let him know that if he cheats on you during this process of rebuilding, that it will end and you will file for divorce. I don’t say this to encourage divorce, but rather to help you save your marriage. A woman who is not prepared to end her marriage under the conditions of a husband who repeatedly cheats on her will have a husband who always cheats on her.
Professional help
I have helped thousands of women reconcile with cheating husbands through this method of good boundaries and good connection. I haven’t seen any women fix their relationships by having poor boundaries or by punishing their husbands. If you want help with either having the correct boundaries or learning how to reconnect and re-attract your husband, then you may wish to consider getting relationship coaching. On the other hand, if you know you need to have good boundaries but find yourself unable to do it, you may need to get into individual counseling. Trust God, but still do what you can, while you still have the opportunity to do it.