sex toy

I've been with my fiance for about 3 years now. He is my 1st and only, and sex is great but he rarely last long enough for me to finish. He used to go down on me but now seems to just finish and go. I've been wanting to get a vibrator or something for me to use but I'm afraid he will get offended if I do and to be honest I'm a little embarrassed to get one since I've never had an experience with any sex toy. I'm also afraid i would prefer the toy instead of my fiance.

Any advice??