How can I become more accepting?

My friend recently entered a relationship with a guy she met at college. She's being seeing him quite often and just like every conversation we've ever had, she wants to tell me all about it. I, on the other hand, don't want to hear about it because I do not care for this guy and I am suspicious of his intentions. They've known each other for two months and are now moving into the third. I still hold my reservations towards him and while my friend knows, she's still pursuing her relationship. As a result, I'm still not okay with it, especially since it's moved so rapidly. I don't want to feel this way and have a strained friendship because of this one guy. While I'm not going to be okay with him, how can I be more accepting?