Emotional Permanence Advice?

I have BPD and I am significantly better than I used to be. I am able to have stable relationships and good communication so I thought I'd be fine in this new relationship but I am struggling. I really like this guy but now he is gone in another state for basically two months. I randomly start questioning my feelings for him. And I start to get worried I made a bad decision to get into a relationship with him. But then we call and it feels like everything is fine and I am positive I like him. I don't know how to deal with the lack of emotional permanence making me think I am losing interest. And I am scared it will make me ruin or lose this relationship. What are some tips to alleviate this?