Help with my sex life

Okay ladies is it just me or when ur husband or boyfriend, or wife or girlfriend seems to not be interested in giving you any sex at all what so ever that they have interest in someone else? Like we have sex, and then I start my cycle and then boom no more sex, in what feels like a whole year. It really sucks, and I'm starting to believe that men don't understand that woman have sexual needs as well as them. Tell me your thoughts please and don't leave anything out, I need some help with not thinking he cheating all the time