She’s not interested in you romantically. She’s probably just being friendly. It’s already clear, even from what you’ve said yourself, that she prefers talking to your roommate more than to you.
Maybe she enjoys talking to your roommate more because she has more fun with him and feels more relaxed around him. You mentioned that you tend to be serious and often get jealous, even though the two of you aren’t actually in a relationship.
Honestly, I’m even surprised that she hasn’t started avoiding you yet. To be honest, you’re being a bit too persistent. You two aren’t together, but sometimes you act as if you are.
If I were you, I would start moving on and stop bothering her. Giving her space is probably the best thing you can do right now. Who knows, she might even change her mind someday if you stop pressuring her, but you shouldn’t count on that. Focus on yourself and move forward instead.
