As Ross keeps saying in "Friends" - they were on a split-up. Or rather, they weren't - they were separated.
Ok. Personal anecdote.
I met a very nice man. And he really was, genuinely, nice. I became friendly, just that, with him.
He had split with his wife, and they shared custody of their child. In fact, she was the one who had initiated the separation, but it was amicable. Indeed, she was dating other men. He was dating no-one.
W bacame closer, and I was contemplating becoming even closer.
But I didn't. Why not?
One night, a woman approached me at a party, introduced herself as the ex-wife, confirmed all the above details, and then proceeded to inform me, in a not-so-veiled way, that she "checked-out" all her ex- partner's potential new girlfriends, and was prepared to beat up any that she felt "weren't going to take him seriously enough" or might "emotionally hurt him". She was "protecting" him.
I decided, then and there, that, lovely though this man was (and he really was,) he clearly had had the misfortune to attach himself to a scary, scary lady, when younger. And whoever tried going out with him would have to deal with her. Presumably for a long, long time.
This was, clearly, why he had dated nobody since splitting up. She was committed to ensuring he had no personal relationships, other than with her. Even though they were not together, she was controlling his life by terrorising women. Nice.
She had absolutely no right to do that. And nor do you.