"My girlfriend has gone off sex since buying a monster-size vibrator. What can I do?"
My girlfriend has recently invested in what I can only describe as a monster-size vibrator. Since the purchase she has gone off vaginal sex with me and seems to prefer to just give me oral sex while I use the sex toy to penetrate her. Is this a case of bigger is better and I just have to accept that?
You don't say how long ago she bought the toy, so it could just be she's enjoying the novelty of it. Or she might enjoy the feeling of being penetrated fully and deeply by a vibrator so large, no penis is ever going to be able to compete with it.
This isn't rare but it is unusual. Most women aren't interested in being penetrated by enormous penises (or dildos) because most women have orgasms through clitoral stimulation.
Given the clitoris is outside the vagina, rather than inside it, you could penetrate with a barge pole and it still wouldn't have the desired effect!
While the feeling of being penetrated is extremely arousing, most of the nerves of the vagina are concentrated in the first inch. So you don't need a very big penis to stimulate them. The vagina also balloons once aroused. It's small at the entrance then becomes a balloon shape inside. Few penises are wide enough to touch the sides at all times.
Your girlfriend obviously likes this feeling, though I have to say the turn on for the monster vibes is often the head-game. It's wanton and forbidden and naughty and most unladylike to like this sort of thing, which is why your girlfriend possibly enjoys it. The vagina is elastic enough to deliver a baby and spring back to shape, so I doubt it's going to ruin her for usual penile penetration and if it's something she enjoys, it's something she enjoys.
Most important is for you not to feel that your penis has been replaced. And to make it clear to her that even if she's gone off intercourse with you, you haven't stopped liking it or wanting it and there needs to be a compromise.