Oh yes, they never tell you anything more than you need to know.
For me it went like this....
I noticed he was less available, quite hyper at times as well.... Sometimes quite smug? I knew something was different and asked about it but it was all in my head according to him...
Then he said he was skint because of everything he had been paying out for, I was confused as I knew of no extra expenses. When I asked what they were he said " just bills"... I let it go but it was odd to me. I found out later he spent thousands on her.... ( And she was married as well).
Then I just got so suspicious I wouldn't let it go, I actually ended the relationship because I just knew something was wrong, he contacted me days later and said he had a one night stand that he felt so guilty about ...
And then it turned into someone he saw three times , but slept with once....
And then it turned into a relationship that went on for a few weeks .....
And then it turned out that he was still seeing her after four months!!! On the day he was telling me all this he was seeing her!. (It went from a one night stand to a four month relationship over a couple of conversations, and it was because I have a very good memory and kept asking about things that didn't add up)
And then he asked me for advice on how to stop feeling guilty that she was married. Lol. You couldn't make it up.
When I split with him , I didn't know for a fact he was cheating but I really felt he was... I never got back with him after finding out he did cheat. I was grateful to have the truth, but then I realised truth isn't something I would ever fully have with him. You need to walk away, you deserve so much better.