sex while pregnant.

i have been feeling like my bf doesn't even want to touch me anymore. i try to get on him and he makes and excuse to get me off of him. then I said how he never has sex with me and when I try he pushes me off. he then goes to say how I'm 7 months pregnant and people who are pregnant don't have sex all the time. i honestly have tried coloring my hair and getting a fresh cut and I thought he'd be more excited to jump on me and hasn't even tried getting on me since. it honestly makes me feel so depressed because i have stretch marks all over and gained weight. help...