His Brandy is correct.
Karma, this is NOT sounding like a healthy relationship, and doubt that you can convince him because either he would already be convinced to call or spend less time away, or he's never going to treat you better.
And please don't convince yourself this is an "up and down" thing... NEVER should you be with someone who is completely insensitive to your needs and pain. You said, "Like i don't even exist to him," ...that to me, sounds like an abusive situation. If you are in a relationship with this guy, you have every right to be able to talk things out with him, to have time together, and be treated with common courtesy... i.e.... calling when they are gone long and letting you know where they are.
If you earn enough to support yourself, i think you might want to consider ending the relationship soon. I know you love him, but it's not worth the pain and what it's doing to your self esteem! If you don't earn enough right now... i'd start working on it immediately.... sounds like it would not be much to him to leave. All he'd be missing is a shower, and he can get that somewhere else. If i were in this situation, and he weren't responding to the needs of the relationship (and he isn't)... i'd change the locks when he's out "wherever."