please help!

I was just wondering if anyone else went through periods of not being horny. Like last night me and my boyfriend of three years had finally had alone time because we both work Monday thru Friday and are always tired when we get home so we haven't had sex for at least two weeks which has been awful but as soon as we actually had the chance, I didn't want to do anything. Like nothing could make me want him. This is the first time it has happened and I just find it so strange. All I could think was finishing him so I could fake it and it'd be over. I love sex and love everything we do but for some reason I just haven't been into it the past few days. So if anyone has any advice or has gone through this and knows how to help, it'd be greatly appreciated