He's had 20 failed relationships.
I sincerely hope that's about to become 21, OP.
There is no good outcome for you here - unless you actively want to be a single mum with no emotional or practical support, just a grudging financial contribution?
I'll take a wild stab at armchair analysing him from the little you've said. He wants the surface advantages and benefits of being in a relationship. Someone who can listen to his rants about horrible colleagues, bureaucracy, politics, the news, the dearth of parking spaces in town. Who he can boast to about his petty victories at departmental meetings and the plaudits he receives in his field. Someone to give him admiration and an ego boost, and soothe his frustrations. Someone to have sex with when he feels like it, and he doesn't like condoms, so he'll pretend to want a baby and marriage so that he doesn't have to wear one, in the sure and certain knowledge that if a pregnancy happens, he can just fuck you off if he's bored of you, or keep you trapped with him (without marriage) if you're still useful. After all he's getting older so needs to think about his care needs going forwards. A younger nursemaid would be very useful.
What he doesn't care about is you. You are not a human being with needs, wants, agency, or even a personality, to him. You are a combination of mother, sex aid and housekeeper. When you start breaking out of this role, he punishes you by going cold until you get back in your box.
Life with him would be a life of servitude, of suppressing your own desires and serving only him. Get out. There are literally billions of eligible men in the world. There is no shortage. As a woman without children in her early 30s, you are sought after by men who actually want a relationship of equals.
Extra bonus armchair analysis: I suspect he has/had a very unhealthy relationship with his mother.