Advice on if I should continue this weird dynamic I am in. On and off for 2 years

I’ve been seeing this guy since December 2023. I’m 25 and he is 28 now.
At first it was just casual because he was getting over someone and I’d come out of a 7 year relationship a while before.
He was sleeping with others and I wasn’t.
I slept with one person in May 2024 (we still hadn’t said anything about feelings towards each other).
June 2024 he says he has feelings for me and I confess mine for him. We then start exclusively dating. I go away for a concert after a few weeks and come back to find messages from him to other girls saying he was still single etc. he breaks up with me over it after a month of being in a relationship. But the dynamic between us doesn’t change, just there’s no label.

Fast forward to 2025 (we’d had multiple arguments within this time because I’ve caught him sleeping with people but he says he can because he’s single.) we’d basically been living together since start of 2025, unless we argue and he tells me to go back to my parents.
I go away for 2 week holiday and whilst I’m gone he puts so much affection and love into our dynamic. Says he wants a family with me, misses me, dreams about me, loves me. When I get back we try again for a relationship, 3 weeks later he breaks up with me. He says he just doesn’t want a relationship and never thinks he can be with just one person.
But again, the dynamic between us does not change, we still live together, act as if we’re together, my family/friends and his think we are. I cook/clean/ do the food shop etc. he also struggles with alcohol so he has good and bad days.
His family tell him I’m the best thing to have happened to him and he’s lucky I’ve stuck around for so long.
Bare in mind this whole time aswell online he acts like a completely different person, you’d think he’s single, he doesn’t post me when we go places, just himself, I have never made it onto any social media post/story.

Whenever we argue he says he’s done with me, he brings up the one person I slept with back in 2024, tells me to take all my shif and never wants to hear from me again, tells me he hates me. Says I’m a red flag because he slept with me the first time. But whenever I mention any of the numerous people he’s slept with since we said we liked each other, he just tells me to F off and get out. I’ve caught him out in multiple lies about meeting/being with other girls. I’ve always left him to message me back when we argue.

Fast forward to two weeks ago, he gets back from a lads holiday and says he’s had an enlightening time with them and they’ve made him realise he needs to be nicer to me etc.
fast forward to one week ago, he tells me he wants to start exploring other options and he says he’s talking to someone already and he enjoys the chat, they’ve been talking since just before he went on the lads holiday. He tells me she’s told him he likes her and he said he can see himself having feelings for her. We get into a heated argument about it and he says when he looks at me he doesn’t see a future. And he loves me but not in the romantic way which I want. He says he loves being intimate with me but the “spark” isn’t there. He knows I am head over heels in love with him.
I take him to an event to go see his friends and he goes dead silent over night, turns out he’s blocked me from his social media platform and has posted this other girl on there and didn’t want me to see.

We’ve argued about this every day the past week. I say I can’t carry on this way because it’s not fair to me or to the girl. He’s lied to her already saying I’m just a “FWB” he sees, not that we basically live together etc. he says he doesn’t want me out of his life and is confused about it all. He says what if it doesn’t work out with her etc. he says even if it does, he will still be friends with me and see me because she can’t tell him what to do, but out of respect for her, if things got serious between them I couldn’t allow that because it is not fair to her. But he says if I move on he’d block me and would never speak or see me again and pretend I never existed. He’s also said if I say anything to this girl he would ruin my life. But says his loyalties lie with me because I’ve gone through some pretty tough stuff with him and know a lot about him he’s not allowed anyone else apart from family to know.

What do I do? My heart yearns for him. But I feel it’s unfair to myself to be stuck in this spot of being a “back up”. Or not even that because he does not see me in the same way I see him. Would it be possible to ever be friends with him in the future? Do I back out completely now or slowly or leave it as is?