Need advice about my feelings

I (17F) have been with my boyfriend (18M) for 3 years. We’re in a long-distance relationship.
Whenever he goes to sleep, I used to get really upset and cry. I knew it was because I had an unhealthy emotional attachment. Over time, though, those feelings changed. Now, instead of feeling sad, I get irritated, and I end up not wanting to spend time with him before he goes to sleep.
I don’t understand why my feelings changed like this. I don’t want to be angry at him because he hasn’t done anything wrong. I just want to understand what’s happening and deal with it in a healthier way.
Has anyone experienced something similar? What could be causing this change, and what are some healthy ways to work through these feelings?