Are あなた serious? That's wrong on so many levels. You're gonna just break up with your boyfriend just because somebody else asked あなた out. That's messed up. あなた figure out what あなた need to do. I'm not helping あなた with your soap opera shit.
Umm no! What kind of girlfriend are you?! To been consider breaking up with a man for his own friend! that is so shallow and rude. Not only will it wreck your relationship with guy one but did あなた even consider what it'd do to their friendship. Gosh if I were him I'd end it with あなた here and now!
Have あなた ever thought about breaking up with Dom before this? Was it because of other boys? What kind of person is Tyran and would he make a good boyfriend? (I'm going to assume not. What kind of person asks out their best friend's girlfriend?) Are あなた happy with Dom? If あなた have to even ask this question, I doubt your relationship with Dom is very strong.
But only あなた can answer this question. Think about how each boy means to you. Good luck.
Also, I would recomend asking for アドバイス at link 次 time. People at this spot tend to be a bit harsh. ;]