Why’s he saying and asking me this

I have been dating my boyfriend for a few weeks now and initially he was telling me all of his exes had cheated on him and the stories of how he caught them like one girl was working in a bar the bar closed at three and she didn’t stumble in till 5 o’clock in the morning and he accused her of cheating and she admitted it I guess and he asked me you wouldn’t do that to me would you????? cheat on me?? He said I don’t want to be cheated on I want someone that’s faithful like I am I’m not a cheater...

He also rambles on about his ex-girlfriend and they’ve been broken up for a year about how she did drugs and would overdose all the time and all the stories about her and I told him I don’t want to hear about her anymore