Okay, all fictional characters EVER. Repeat after me: When I meet someone new, someone I am sweet on, I do not own THEM, their HISTORY, or their previous romantic relationships. Except insomuch as it informs the anti-STI precautions you take with them, which you should always take anyway, it does not matter how much they dated, fooled around, or were serially monogamous, as long as it was in a consensual and respectful manner. I don't care if a guy was with one girl for ten years or ten girls for a day, if nobody got hurt, you don't get to be jealous of the previous lovers.
And that goes for all genders. SERIOUSLY. People's lives and hearts aren't yours to OWN.