From extensive bittersweet experience of my own (long gone, thank goodness), there are men out there that know exactly how to play womens' emotions like a fiddle.
Its not just about the sex (although that is usually the pinnacle of their 'achievement'), its about making you fall in love with them. Swept off your feet with them, putty in their hands, etc.
Men like this know that its all about making you chase them, and not vice versa. So he will make himself as attractive as possible in your eyes (hence the 'honourable' agonising and displayed 'unavailability', whilst at the same time gradually inching closer).
I had a 'romance' in my life, where I was convinced the man was a tortured, honourable soul... misunderstood by the world and lonely. He wanted me because "only I understood him", I made him "feel things he'd never felt before".
He even went so far as to tell me he could not be sexually active because he had been molested as a young man and never recovered from it.
This led to a very long period (years) of me mistakenly trying to help him through his problems by building up sexual activity with him. I was desperately in love with him, and felt like I was holding a wounded little bird in my hands.
Except it was all a lie... the entire relationship. Its a long story, but essentially he had between four to six other women/young girls on the go at the same time as me, using exactly the same spiel, and a whole string of exes that had already been through the 'game' with him.
He was so convincing, and played the wounded victim part so well that if anything I'd felt I was the one pursuing him, I was the one who initiated everything sexually (I wasn't in hindsight, just manipulated into it).
The red flags were there but I hadn't payed attention (him not wanting me to meet his family, maintaining a lot of distance - I couldn't easily contact him whenever I wanted, blowing hot and cold, over-the-top romantic gestures and words, drawing close and then backing up just far enough for me to chase him... etc, etc).
I wish you all the best OP, I really do, but please don't underestimate the thrill of the game for some of these men, and by telling you he won't leave his family he's already set you up to be the 'chaser' and himself the 'chasee'. Now all he has to do is stoke your fires up just enough from time to time to keep you running after him, while your other relationships wither into ash. The more you lose (or give up) for him, the more powerful he becomes over you. 