I love my gf to bits, and we have a great sex life. Except - I literally can't feel a thing during penetrative sex with her. There's so little sensation that I can't even tell if I'm inside her. If I penetrate her from a really extreme angle then I can usually get a bit of sensation from one side. She's had a couple of kids, and I know that can cause changes down there. But so have most of my previous partners in recent times, and never experienced this with anyone else.
Because of this I rarely orgasm through PiV with her. Sometimes I make it, sometimes I fake it (just tell her that I came when she asks), often we just give up without finishing. She always has a couple of orgasms herself before we even get to PiV, so she's always satisfied, no issue there. And she enjoys the penetrative sex, usually has more orgasms, so I don't think she's aware of any lack of sensation.
Early on in the relationship she asked if it was her fault that I wasn't reaching orgasm during sex. Obviously I lied and told her that it was entirely my issue (and anyway, at that stage I wasn't aware of the looseness, just assumed it was a lack of sensation on my part). I'm not sure if she believed me, but I know she finds it immensely frustrating when I don't orgasm (as do I).
But I've come to realise that inside of her vagina has a very large diameter to it, there's no tightness at all, just the entrance which does feel normal. When I stimulate her with my fingers I can put 2/3 of them inside her and spread them right out without any resistance or being able to feel the both sides. Now I think my penis is a fairly average size, but even if I had a massive one I don't think it would touch the sides here.
I know she did have some tearing during birth of her last child (10 years ago), and had reconstructive surgery, which I presume was successful for that issue. She's also due to have more surgery in that region in the near future - for something totally unrelated, but which is will affect vaginal shape/support. So there's a real chance that could make things even looser.
We talk fairly openly about intimate matters, but I just don't feel I can tell her about this. I've hinted at pelvic floor/kegel exercises a few times, but she doesn't have any continence issues so doesn't see any need for them. I think that also suggests that an internal prolapse couldn't be the problem?
Everything else in the relationship is great, and the passion and sexual chemistry is amazing apart from this issue. Is there a way to broach this subject without offending or upsetting? Should I just keep my mouth shut and keep faking it?