No Sexual Desire??

Posted anonymously, as I'm incredibly embarrassed that my sexual desire has almost withered away to nothing with my current SO of over a year and a half. We've had a lot of difficult things come our way the past few months and we're handling it well, however, I can't seem to find the same level of sexual desire anymore. Is it something I should see a doctor for? Or is it because of my relationship? Possibly any other suggestions?