25 weeks and can't stop crying

I'm currently 25 weeks pregnant and for the last 3 days I can't stop crying and getting a hold of my emotions I have no reason for it I just feel so unloved by my fiance and everyone and just can't stop crying I hate it because I have no reason to feel this way I know he loves me but I can't help but cry because I'm terrified he doesnt and is only staying with me for the pregnancy. Has this happened to anyone before ? He gives me no reason to feel this way but I can't help but feeling this way ..