<human>: Can you give me a shortened version of the text?

We met in college, she's gone on to grad school in Colorado, and I moved to Denver for the culture (love big cities) and in part, because she was going there too. 

My problem now is that my job leaves me utterly exhausted both mentally and physically. While I'm normally sarcastic, up-beat, and charismatic, this job leaves me short, tired, and beat down. Obviously this isn't helpful to our relationship.

I've taken some time to evaluate the problems and I came up with a few reasons (beyond my job) that are causing problems for us:  
1. We're at different points in our lives, and it's quickly becoming apparent that we don't have much in common naturally.  
2. She complains about the symptoms of our problems rather than root causes.  
3. More importantly, it's never constructive criticism, which just puts me on the defensive end.  

I'm looking for another job, and I only took the one I have currently because it paid well and let me essentially move from the college town to Denver. 

I've also lost interest in our sex life and on more than one occasion I have found myself thinking of other women sexually although I would never cheat on her. I think cheating is just selfish. 

Basically, I want to be happy again and all signs point to us breaking up but this is the longest relationship I've been in and so I don't know what the best course of action is frankly. I'm tired of fighting, and just tired all around. I've told her that we need to find some new common hobbies or something but so far we've come up with nothing although I don't know that she has put any real thought into it because so far she's come up with nothing.
<bot>: Multiple factors in a failing relationship. How can I reignite the fire that we used to have, or should I just break it off?