I don’t think you have “trust” issue. I think you have “lying partner” issue. I see no reason to learn how to trust liars. What for? I see often on this board people complain about having trust issues due to have lying partners. They have wrong partner problems not problems with trust.

But I think main issue isn’t even lying. It’s more like settling for wrong partners. Now this guy clearly loves to follow these women. That’s who he is. Asking him to stop doing it causes him to lie because that’s who he is: a guy who likes to follow women. People don’t typically stop doing something because they are given ultimatums. They either don’t do it because that’s not who they are or because they want to stop.

I encourage you to not try to change this guy but rather find men who are more suitable as long term partners. I highly recommend that you don’t marry this guy and certainly don’t bring kids into the mix.