Relationship is going to shit

We have been togeather for a year and a few months now and are living togeather and the past 6months or so he seems to be annoyed with me about everything and his sex drive has gone to shit. Im the beggining he was the sweetest thing and showed me he loves me all the time an now i can't seem to do anything right without getting belittled or called annoying. Id if it is a phase or how to fix the underlying problem it is hard to talk to him about it without him getting mad or telling me im over thinking.