Have I posted this before - oops. Sorry. Not often I contribute.
So far!!
Maybe he just is scared stiff of doing something he appears to have regretted from the past.
You write that you've otherwise a reasonable relationship. And you do want to have sex with him.
How else could he convince you? He's asking if it's ok. Checking with you. He's not repeating his mistakes, is he - your responses say not.
He wants to have sex with you, and you with him. Sit down together, go away overnight, a weekend. Rewrite the clarity in your own (both) acceptance & agreement re sex.
Tell the numptie that each time he asks first to 'check' that he's perpetuating the problem & screwing it up for you.
So;
rule 1). Don't do 'that'.
Rule 2). But do "that" more often, gentler, harder, longer etc.
You write you have someone who is worth having in your relationship. Work at it. Start afresh. He got it wrong. You're moving forward. Don't perpetuate the negatives & harp on about the past. Do things differently. Lay the past behind. Both of you agree this together.
Is there anyone who can say they've never asked/wondered/wanted to try/ proposed their own agenda, NOT in a demanding or abusive way, but exploring?
His exploring (cause he had whatever 'problem' you mentioned) may have been desperate attempts in too focussed a manner to overcome HIS problem.
And he lost sight of where he is/was and that turned out to be abusive upon you. WRONG fella. Totally wrong.
But, consider that he absolutely wants to make amends. That he's piss poor scared of repeating mistakes he genuinely didn't want to generate in the first place.
Your call. If you believe he is genuine in not wanting to replicate the mistakes & damage he perpetuated on you then find a way forward. It SHOULD get better. . .
I agree, Jaxhog
"Stop apologising. Just tell him you'll let him know if things go too far. And do it".
A sound, health, mutually agreed between you response.
Hoping it all improves. 