Vibrators in bed: My boyfriend is apprehensive?

We have tried many times for me to have an manually but its just not happening. I can have an easily in the tub with running water. I read that some girls have a more hooded oris so they need more stimulation than what a guy can do manually. i mentioned bringing a tiny vibrator into the bedroom a few times but my boyfriend got quiet and weird about it all 3 times. Now he's made me uncomfortable about even bringing it up and i feel trapped. i"m afraid if i keep dating him i might end up in an less relationship. what should i do?