Can I have long-term girlfriend and mixed feelings at the same time?
Mix feelings? Are you thinking of breaking up with her?
No, I still think I love her.
I'm sorry you're having doubts, and those are all valid to have. But you need to open up and talk your problems out or these doubts may become a reality and your relationship will crash down.
Thanks for the support even though you don't know what I'm saying.
I would love to better understand what you are trying to convey, but from what I can tell, having mixed feelings is never good for the relationship. Communication is important in any relationship, so you should do that with your girlfriend. Is it possible that the conflicting emotions are related to the impending marriage?