never in the mood anymore😫

okay so my fiancé and I have been together for 3 years and I just dont seem to be in the mood anymore..I'm 21 and I work some days and then some nights. we are in the middle of renovating a house so I have a large amount of stress. the only time I'm in the mood is when It's my time of the month. he feels like it's because "I'm tired of him, or he's not attractive to me anymore" and that's not the case..idk what to do..any ideas??