I have never heard or seen anything that actually says Boba Fett was actually married to Sintas Vel. That he had the daughter with her, yes, but not if they were married or not. I think most people imply it, mainly because of Boba's discussion with Princess Leia in Jabba's palace, about sex outside of marriage. But, who knows? Maybe he left in order to keep them safe from his own enemies?
Plus, you have to remember, that even though Boba was Mandalorian, he didn't have the chance to be fully immersed in the Mandalorian culture and traditions, since his upbringing by Jango was cut pretty short. Everything after that, he pretty much had to take what he already had learned from Jango and then go from there. That's probably why Boba is considered a better bounty hunter. He's as adept and talented as Jango was, but he's a little more ruthless and driven. Boba has that "growing up on the mean streets" edge to him. Whereas, Jango was raised in the more controlled and militaristic environment, while under Jaster Mereel's tutelage and his warriors.
--Sadriel Fett (BFFC Moderator)
"I'm just a simple Fan, trying to make my way in the universe."