Some thoughts that comes to mind for me about Jasmine. Besides being a very pretty woman. For the MC, Jasmine has been nothing but a sweetheart, helpful (yes, Charles had her help MC at first, but was still nice about it in the end) and friendly, welcoming MC with open arms. Also, Jasmine is one of the first characters the players meet and greet after moving to WVM, The very first girl you meet on Day 2 arriving at WVM, so that's a possible reason. As for many stories in general (In Games, Movies, Novels, Anime Series, etc.) there usually seems to be a favoritism of some kind for the couple of first girls introduced to the players/viewers (This can said for Jamie & Shauna too, alongside with them being MC's main girls).
I don't agree with the "steal his girl" statement, as MC isn't stealing Jasmine away from Damien. MC never crossed that line and never tried to seduce Jasmine at anytime when she was still surely with Damien, MC just offered his opinion on their situation as diplomatically as he could. Jasmine and MC have been more best friends to each other than MC and Damien has been. Before MC even got to know them, Jasmine and Damien relationship was already on the rocks and after MC met them it was reaching its breaking point. We've been told and shown that Jasmine has been neglected multiple times by Damien in their relationship, like ditching her with no explanations, standing her up for the pool date, not being upfront with her about his absences and behavior, and even having her feel overshadowed by him when she talk to other people with Damien always end up being a topic point as if she doesn't exist. To me, those actions alone are more than enough to end the relationship than the alleged cheating and his questioned sexual orientation.
She was unhappy, why she hasn't been left him by now? Well, some people (Not all, but some) in relationships they try to hold out for the best outcome, especially after being together since high school into college, she was probably given Damien the benefit of the doubt. With that you could also argue it's because Jasmine is a kind person, maybe too kind to just kick Damien to the curb (Maybe kind to a fault like MC).
After meeting MC and seeing how he treats his girlfriend(s) and others around him likely made Jasmine come to realization of her current relationship and situation. She even said she need someone like MC (a clone in fact), someone who cares about her and makes her happy, giving her the time of day, showing her love and affection. Then, the ordeal of Damien telling Jasmine not to come back to the home they shared was the final nail in the coffin. After that, the reveal that Damien is working with shady people like Ryker likely reaffirms Jasmine's decision to move on. To me, Jasmine clearly had no involvement in Ryker's business, innocent and deserves all the sympathy.
Back to MC and Jasmine relationship. MC without crossing the line, as a friend has been giving Jasmine some of that care, love, and attention she's been wanting for so long now. Listening to her and giving his advice to two-cents and both helping each other in some way whenever possible. Hints of mutual attraction between the two. When it was clear she and Damien where done and her showing interest in MC, it gave MC & the players a green-light and reason to want her more then already without any love triangle drama. I'd said Jasmine scenario can show how some people after a breakup can move on quickly to a new relationship, especially when the previous relationship was basically nonexistent with the end being long overdue.
Well, that's just my perspective regarding Jasmine. We all view things differently, by no means I'm trying to change your opinion.