Sex drive decline

So my boyfriend and I have been dating for a little over a year. We moved in together after dating for 7 months and while the transition from dating to living together was difficult sometimes, I absolutely love living with him. I am a 22 y/o graduating college in May and he is a 31 y/o, college graduate and Air Force veteran. Over the last two months or so, my sex drive had plummeted and my bf has noticed. We have had conversations about it, but I have no explanation for why my sex drive has changed. I have no idea why this happened or where it came from, I am still extremely attracted to him and very much in love with him....anyone else have this happen to them? Suggestions? Thanks for the help!