I'm (f23) in an open relationship with my (f23) gf. We opened the relationship in the premise that she wanted to explore her sexuality and maybe in the process, I'd get to do that as well. We tried exploring but I'm really more on the loyal side and can't get aroused with anyone other than her. Meanwhile, she's having sex with a workmate from time to time and she doesn't really think anything about it. But everytime she did, it hurt me silently. I thought that that's just how it's gonna be for a few times and that I would feel compersion eventually. Sadly, I think it made me just care about her less.

Now I've been talking to people online and I've become "friends" with this man (m22). I say "friends" but really we know it's something more than that. I've been honest about the situation that I am in and I've told him that I'm not breaking up with my gf just because of a fling. I'm more committed to my gf and it's really ugly to end a relationship to start a new one right after. He understands but he feels like we won't be going anywhere since I have a gf and he doesn't want to be in an open relationship. He's a date-to-marry kind of person so he stopped talking to me. We both understand that it's for the best.

Absence just made the heart grow fonder. I just kept missing him. Crying over it. Just thinking about him and what could've. I love my gf but I kind of feel more affectionate to him. He makes me just want to be loyal to him, settle down, have a family. Idk what to do about this.

Should I just suck it up and accept everything? Or should I end my almost 3 year relationship (3 years at the end of the month) because I'm confused?

Tldr: I'm in an open relationship with my gf and I think I'm in love with a fling. Idk what to do with my feelings.