sexually frustrated

Ok so lately my bf hasn't been good in bed and it's really starting to piss me off. Most of the time I actually get off is because I'm on top and make sure I do before he does. I'm so sexually frustrated that I'm thinking back on all the dudes I turned down because I was with him. Obviously I love him and don't want to end it by ANY means. Just really frustrated and I find myself getting in these moods and giving him all kinds of attitude which starts arguments. Although he claims I don't give him any cues if he's doing a good job or not. Some one help me out before I buy a vibrator !!