Help!!! My Emotions Is Destroying My Relationship And Sexual Life.

I don't even know where to start. Anyway i have been dating my man for close to 4years now and we are both cool together and we planning to get married after am done with my youth service. The number one factor why i decided to have like a distance relationship with him was the fact that i didnt see myself dating a guy from my school, so i choose him, tho he lives in same town with me we do not see that often cos of school and other stuffs.
I am introvert and i deal with mood swing and emotional problem even when my guy is around i sometimes feel like not going to see him because i feel like am not in the mood to see him, i say something like "you saw me last week/2weeks ago why do u wanna see me again?" I love him so much and i dnt even have what it takes to cheat so i have not for once in our 4yr course cheated on him. My attitude almost broke us up last year cos he felt like he was not loved the way he ought to be loved.
I also have problem with sex, he is the first and only guy since we first had it together but i always feel like he is dating me for sex even tho its so glaring that he is not. We dont usually have sex cos we dont see often. Lets just say at most two times in a month which is rare or lemme say three times in two months which is also rare, but going by this i still think he loves sex so much. My emotion always come first before or during sex, little thing easily piss me off, i remember a night we were about having sex but i stopped him simply because my system spoilt a day earlier and i felt like sex is the last thing on my mind, sex is always the last thing on my mind I may even start crying after sex if my guy doesnt stay in bed to cuddle me, he is a faithful guy and i dont want to lose him to my emotions.
I dont see myself going through all these after marriage, is this how i will be depriving my husband of sex just because of some petty stuff that should not count in the first place? My baby is coming home after over two months now and i already feel like am not in the mood to have sex or anything. Is anybody going through this? Please i need help bfr its too late.