Confused :/

So me and my bf have been dating for a little over 5 months and we would have sex a few times a week but it's been about 2 weeks since we have had sex and I don't know why :/ it's not that I'm mad we haven't but I'm just worried on why.. he still gets boners and stuff around me when we hang out and we hang out every other day.. I just don't know why the sudden change I guess and I don't know who else to talk about it with I guess :/ and I know I should talk to him about it but the one day he made a joke saying I was a sex addict and after that I don't really want to bring it up... I'm just upset over why he lost interest in sex out of no where..