Attachment style isnt a flaw though. It's a style. He just needs a partner who works with his style...
The thing is, its massively disrespectful to a person to get with them, and then try to change them.
If they want to change, then they change themselves.
Changing "for" or even "with the help of" another person, that never ends the way people think. It is usually wine and roses for a few years, then the energy runs out, the person reverts back, and starts grumbling about how they have been manipulated and nagged.
How long did you know this guy? Because I married a "project" sort of man, the type who needed renovations and who asked for them. After we had a baby, he completely changed his tune and rewrote history that I was a controlling harpy. When in fact all the decisions and changes he had taken had been his own. My crime was supporting him and praising his changes... that was 11 years of my life that I will never get back.
I think the thing to remember is that relationships don't need to be this huge source of change/work/slogging through "issues". There was 3.5 billion males in this world. Women do not need to take on fixer uppers. When they do, they need to ask themselves why they equate love with labour... love can be very simple and rejuvenating.
And men who present themselves as fixer uppers are also caught in a silly belief system. They're frequently very manipulative and demanding, often not consciously, but still in a way that is so destructive to themselves and others. And THEY are in charge of that - not women.