Struggling with Separation Anxiety in a Long-Distance Relationship

So I started dating this new guy recently. I really like him, but I don't want to give my hopes up again. being in relationships is really hard for me because I feel I'm too attached or too distant. I have severe separation anxiety because whenever I'm far from someone I love they leave. He is my world and I don't want to push him away. I have so much going on with myself and it feels like I complain too much and that's what pushes them away. I want this to be perfect, because he is awesome. Now he is graduating next week and is supposed to go into the Navy next month. I'm scared that he is leaving. Not because I'm afraid he is going to cheat but because it's going to feel so empty without him around. like he can't even message me for three months. I just keep planning to get multiple jobs to keep myself busy so I forget that he isn't going to be messaging me good morning and night. I really don't want him to leave. This is my last true summer, and I can't even spend it with someone. I thought this was my year to relax and enjoy it. But I'm just going to work and sleep it through. I'm taking college classes and conditioning for heavy lifting so I can get a factory job and make a bit of money, so I can buy my first house after I graduate next year. sorry this is a bit much of a rant, but I'm really going to miss him.