He recently said he wants to wait 6days?

Been in a relationship for 6 months we've had sex everyday almost .I do everything without him asking blow jobs sex cooking cleaning etc everything was great .This one night he gets home he says he doesn't want sex three days pass it seems as if he trying to argue on the days we didn't have sex .He's always on his phone when I walk in the room he puts his phone down today I asked were we going to have sex he says he wants to wait three more days wtf I'm assuming he's cheating or he fukked someone without a condom n needs time please help asap.