Okay so this might be a long story but basically I’ve (F 19) been with my fiancé (M 21) since i was 15 and haven’t been with anyone else. All of my friends seem to think i should break up with him saying so directly or indirectly. I find myself envying single people and even fantasizing about cheating on my partner even tho i would never do it. I’m afraid I’m missing something out something by only having experienced one relationship. If things were perfect with him i wouldn’t have doubts but they aren’t. I find a lot of things he does unbearable. He also jokes about and exposes really personal info of mine and my friends even if we repeatedly ask him not to. Some of his opinions go against my morals and he never admits to being wrong. We even had a situation that i consider cheating but he doesn’t. He was saying “i love you”, “xoxo”, and “mommy” to a mommy asmr youtuber that he was paying on Patreon. (NOT MY KINK AT ALL, but whatever i guess i just wish he hadn’t talked to her behind my back.) he’s extremely in love with me and would be devestated and make a huge scene if i broke up with him (which i tried to do multiple times while we were dating). I’d be worried that he would hurt himself tho he has never done that before. I don’t want you to think he’s all bad because i love him and he is sweet and would do almost anything for me and the sex is good and i just want to know if am asshole who just wants to experience being single for the thrill or the idea of someone better because I’m heartless or if it’s something else. He’s not a bad guy and i probably could be happy but for some reason i find myself wanting more, am i the asshole?

Edit: I dumped him. Thank you everyone for the advice. I'm very sad but I know this is the best thing.