Hi Solost123, welcome to PC.

I am sorry you are experiencing this surprise challenge, it's understandable you can't think straight. When you can't think straight you are experiencing confusing emotions while at the same time genuinely don't know what to do about a situation. It's ok to step back and think about a problem and it's good that you thought of coming here too. I think Zkeezkys gave you some good links to read through that might help you have more to consider than just your own feelings and confusion.

Yes, sometimes when a couple is struggling and take a time out, one or both partners might see someone else and may even engage in sex with someone else as well. It doesn't necessarily mean the partner actually even cared about the individual they had sex with either. Sometimes it's more of a check too to see if that area of a relationship was ok with a partner and am I happy in that area. Men don't necessarily view sex the same way women do either, men can engage in sex without needing to have an emotional connection (one of the reasons prostitution will probably always be around).

Also, maybe it's a time to consider if this guy is actually a good match for you when it comes to a long term relationship.

Can I ask how old you and him are?