I would try and believe him. I'm not sure how your relationship has worked, but I was single for most of my life and then met a really great girl who I really really enjoy spending time with and could see myself spending most of my life with. The problem is that I still have mental urges to hit on other girls and I do miss the chase. I have also looked at CL before and to be completely transparent, the site is a complete scam and 99.999% of posts are men or scammers trying to get you to sign up for a paid site to get your credit card info. But even though I've checked it out, that doesn't mean I don't love my girlfriend. In my mind it just means that for most of my life I really enjoyed being single and now I'm trying to transition to being in a steady relationship. I don't want to hit on girls in person and I don't honestly want to do anything, but if I can get rid of the toxic thoughts somewhere else then that's helpful.

What I would recommend is that you talk to him about why he wants to look to CL in the first place? If he wants a chase, what is it that he can't get with you? I think that sometimes I don't want to talk to my gf about like taboo or extremely graphically sexual things I'd like to try out, because I think she might think I'm weird. If you try and get down to the bottom of it, maybe you'll find out something you both want to try out. Maybe you want to role play or try something new out in the bedroom, clearly he's not going to CL for a relationship and it's more sexual in nature. Maybe you both would want to pretend that you don't know each other and set up a date night where you both can explore each other in a different way. I'm honestly just throwing things out there, but I think it's more common then you might think and I highly doubt that he has ever found someone on craigslist. Good luck.

-26 year old male