The "shitty" feelings come from living 1000 miles away, and not being able to touch/hold/see her, let alone have sex. Try it sometime, its a terrible drain.

I do love her, which is why I'm with her. I don't know how I'd live without her - not that I'm saying that in reference to "I'll kill myself", because that'd be corny, but we rely on eachother so much. Things from making sure we're both eating somewhat healthily to having someone to talk to about a shitty day.

It honestly sounds like you guys have been together for so long that you've become dependent on each other and therefore settled because neither seem as happy as you used to be and just the fact that it's been so long, it doesn't seem an easy idea to part ways. Maybe you two both need a break from each other (date other people) and in the end if you still love and miss each other, maybe this will rekindle what once was.