SUBREDDIT: r/relationships
TITLE: I think I have separation anxiety? M&F 19-20 together for 2 years.
POST: I [19F] think I have separation issues. 
Whenever my bf [M20] leaves for work or to go back home I start to feel very sad.  I get tired, depressed, and I just kinda loose interest in everything. 

It starts to happen about a hour before I know he is leaving. I wasn't always like this though. We have been together for 2 years, and I've only started this the last year. 

The only medication of any kind I'm on is birth control. I do have stress issues, I have a bit of a tragic background. He came into my life at a shakey time and made things better for me. 

Does this sound familiar? I don't think I should be that sad. He knows I get sad too, and I feel bad. I know its okay to miss him, but once he is gone for maybe 1 week & 1/2 I tend to just stay in my room and sleep. 

Any ideas what is up with this?
TL;DR: 
I think I have separation issues with my boyfriend. When he leaves I get sad, the longer he is gone the deeper I slip into depression. What is this?