Rome, you sound like an awesome guy. You're doing great. Your fiancé is very lucky to have you; heck, you're lucky to have each other. That's what it's all about, I guess. Sticking together through the hard times. Being there for each other. Great job.
(I was surprised you are only 22 also!)
I think having something to look forward to helps. Plan a really fun date in the near future, hopefully after this semester, for just the two of you. Then you can have that to focus on when you're feeling like this.
I'm feeling this way, too, presently. My boyfriend works a lot of overtime. He has to. He has three kids. We don't live together. We work in the same building, but live an hour apart. So, it gets rough. I am really looking forward to the summer plans we made, though, so that keeps me going.
Hang in there. It will all be worth it!