Guy's Behavior

My boyfriend cheated on me 2 months ago and now he's starting to make jokes about it?

My boyfriend left me and went back to his ex he claims it was because she was threatening to keep there child away from him. he said he didn't sleep with her but mostlikly he did I forgave him after he kept apologizing and telling me that he plans on going to therapy. he started going to the gym 2 weeks ago. today I asked him if I could use his gym membership because i want to lose weight he told me no and made it seem like he was being sneaky at the gym. 5 minutes later he told me he was just joking and only did it because I constantly think he's cheating. and when I wouldn't speak to him after he said he was just joking he told me he don't care I can think what I want and it was just a joke should I be concerned that he's still cheating?
My boyfriend cheated on me 2 months ago and now he's starting to make jokes about it?
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