My girlfriend and I don't have sex anymore?

We have been together for 7 years now. The first 2 years were very rocky, we would argue all the time. I was in a very weird place then and completely scared of what I was going to do with my life. Well, we decided to go back to college together and try to help each other though it.

Well, it turns out we made an amazing team. She help me pass College Algebra with a "B" a class I previously dropped twice before I met her. I would help her in every way I could but mostly with her research papers. We both ended up graduating with honors at the exact same time in Dec. 2010. She earned her teaching degree in Math and I earned mine in Communication Studies with a minor in Marketing.

I love her so much and lover her family too. I had planned to marry her as soon as I found a good job, but finding a job even with a degree was a challenge. She ended up landing a teaching position at a local middle school 4 months after graduation. Well, needless to say I was happy for her but became increasingly depressed. Because she got this job I felt I couldn't look for work outside our hometown. This just narrowed my options, and I live in Kingsville, Texas. It's not exactly a very big town and jobs are few and far between.

Well, after a year her mom said she could find me a job working with (CIS) Communities in Schools. I was desperate and completely bored out of my mind staying home all day applying for crap jobs near town. So I got the job and it turns out I love it. Thing is, her mom is my boss now. Don't get the wrong idea, her mom didn't hire me. She recommended me to apply to for a job opening because she new the old CIS person was leaving from her school. My girlfriends mom is the principle at the middle school I work at. Though her mom can't fire me directly, I can't keep my job if I don't have a good relationship with the administration and staff.

Work is not the problem. I love my job and everyone there is amazing. The kids are my favorite part of this job. They are mostly economically disadvantaged kids whose lives make you appreciate what you have been given.

But back to the problem. My girlfriend and I though we have a great relationship our sex lives are almost non-existent. She works so hard she is exhausted. I always try to get her in the mood but it's just not happening. We might have sex once every 2 months are so. Now, I don't want get married to a girl who doesn't find me sexually attractive anymore. Not only do I think she is tired but I also think she just lost sexual interest in me. Maybe it's because she makes more money then me as well. Maybe she feels like I'm not good enough anymore.