Remember that there is nothing wrong with you for wanting to know the details of your partner’s affair. A lot of couples have gone through and are going through a situation like this, and plenty of them are most likely reacting the same way.
The following are some reasons why the need to know is strong:
1. It becomes kind of a competition. You want to know what your partner did with the other person because it becomes a push for you to do better. You want to prove yourself and prove that you are better. For some couples, knowing the details of the sexual interactions in the other relationship heightens their sexual encounters and brings to the surface some hidden fantasies or desires.
2. It creates a connection between you and your partner. In some relationships, emotional distance creates a barrier that keeps your from really being together, and the affair, or talking about the affair, becomes a reason for you to communicate and reconnect.
In other cases, the affair may be a way for your partner to stir up some drama or get revenge. Your partner brings it up or talks about it a lot to get a reaction from you.
3. You want to be able to protect yourself health-wise, especially if your partner is having an active sexual affair. You need to know the details of his sexual encounters and the extent of protection used, so that you will know if you need to get yourself checked from STDs and so that you can protect yourself against them.