Sex and not wanting to do it!

Okay so I've been with my boyfriend for over 2 years now and we have had sex. I love it but it's been a month since we had it last. That's because I just haven't been into it. However my boyfriend turns me on, like we will have a hot make out session but I just won't want to go further. Is something wrong with me! And I know what some of you might think spice things up maybe I'm bored but we have tried that and it doesn't seem to work. Can a lot of stress make you just not want to have sex? Can your location (aka a dorm room) also make you not want to have sex? Any one have a thought?!