Here's a guy, who's willing to recruit a series of youngsters, and then let them fight alongside him on the streets. So all the arguments about him not risking a loved one, or being paralysed by concern for somebody he cares about fall by the wayside.
I know naff all about the present day Batman, but there are plenty of past versions of Batman where he was portrayed as a reasonably normal mentally healthy guy...there would be nothing out of character in one of those versions becoming happily married.
Not out of character. But outside the "magic formula" that DC has decided must be used to write Batman. Nobody knows what makes him so uniquely successful...so no new major departure must ever be allowed. He won't get married, not in the main continuity.