Sex struggles

Ok.. So I am 28 weeks now.. Not having a lot of sex at all. My mind is always in the mood but once things get started I just don't want to anymore. INSTEAD, all I want to do is masturbate!! I am like obsessed with it lately. I feel so bad because I want my significant other to be pleased but I am more pleased doing it myself! Anyone else or am I just being weird?? Lol