Lost love (venting/advice?)

Marie

This is gonna be a long one, my relationship with this man is so complex I can’t even get it across over text but I’m gonna try my best because my heart’s aching so bad and some outside perspective could be useful and appreciated. My ex and I have been broken up for a little over a month now. We weren’t each other’s first S.O’s, but we were each other’s first true loves. He broke up with me because he says he fell out of love with me, and he thinks there is someone better for him out there. He’s also never been the most loyal, very curious about other women. He’s moved out but we still have sex and act a lot like a couple, we are constantly communicating about it though. He made out with a girl he met on tinder just days after our breakup, but continued to kiss me and tell me I’m the only one. He later admitted to me that he had kissed this girl on their date, and told me that he lied because I was so upset over him even going on a date (I was VERY drunk when he told me) that he didn’t think I could handle it at that time. Even knowing he’s moving on, I still show him affection because I love him. Yet thinking about him with other women wrecks me. I always had a big jealousy problem and I think that’s part of what caused him to leave me. I want to let my jealousy go and just be happy that he loves me even if he’s intimate with others (well, he says he doesn’t, but he acts like he does. He “loves me but is not in love with me”) but he gets jealous too. Is monogamy dying out? Am I crazy for desiring someone who loves me and only wants me? I feel selfish. Yet he was and still is the only man I ever desired. I know it’s about compatibility, but it also wrecks me that I wasn’t good enough for him when he feels like the best person for me and we’ve grown so much together. Yet I’m good enough for him sexually, but still not exclusively. I don’t know if I’ll ever stop loving him. He’ll always be my best friend, and of course I crave him physically or I wouldn’t have this relationship with him, but I know it’s more than lust for me, for him though I can’t be sure. I question sometimes if i should be sleeping with him but we both want to and feel it’s right so we haven’t really stopped. It does make it harder to move on. But I know nothing can last forever.. I’m having such a hard time letting him go, and I think it’s because I don’t want to. I think I deserve someone better for me as well, but aside from all of this I feel like he’s my soulmate and that would make me take him back in a heart beat, so I can’t risk letting go... but this broken heart of mine is starting to drain the life outta me. I see love and the world in a different light now.