Thanks for your post! I really do get what you're saying (although he dumped her twice, and she was devastated, but that's neither here nor there now). And believe me, I've overcome the worst insecurities (thanks in large part to the advice on this site, ironically enough) - when I first came here I was a wreck.
I didn't want sex with her, and I didn't want her to see me naked (especially after she told me his big cock had visually turned her on). We were in a really bad place sexually. She couldn't understand it: she said she genuinely didn't care if sex was better with him because she loved me now. I didn't believe her, & I found it incredibly insulting when she tried to defuse things by saying 'ok, so he filled me physically, but you fill me emotionally'. Fuck.Off! A parent, sibling, child, best friend fulfils you emotionally - the man who gets to sleep with you wants to know he's doing something more than just sticking a hotdog down a hallway for 5 minutes a week and fulfilling you emotionally!
For several months I kept the sex toy business running - you have no idea of the money I spent on dildos, vibrators, extenders, you name it. She wasn't interested. In fact, the only thing that interested her was a vibrator. It gave her a clitoral orgasm, same as I did - so what was the point? Anyway, things got so bad I started making excuses not to have sex, which depressed her. Yet, she's always said she's happy to go without sex physically - she only wanted it because it maintained the emotional connection between us. She really doesn't know how lucky she is: she has orgasms every time within 5 minutes of sex with my 5 inch cock, and obviously has a very sensitive vagina as she feels anterior fornix stimulation and has never had her cervix hit by big or small cock. And less than a minute of g spot stimulation has her shouting for me to stop as she has to run to the bathroom. Man, it drives me fucking insane!
But that said, and despite my response to your post, I can honestly say I now believe her when she says: size doesn't matter enough to make a difference. She felt fuller, more stretched, more pressure, as well as better, more intense orgasms with him, complete with 'back wall contact' - she feels none of that with me. Yet I now believe her that my size was always going to be incidental - she wasn't after a nice guy with a big dick, like her ex; she was after a nice guy, and if he had a small dick, she'd make do for the rest of her life without much of a sideways glance.
My questions now, and my continued preoccupation with LPSG, aren't related to insecurity, but rather a real interest in how sex works for women (which is why I take such an interest in posts by the likes of AlteredEgo). I've made peace with the fact that I'm never going to change my gf's views on sex. She sees the sex with her ex as a pleasant memory that is consigned to history. And if it was left purely up to her, we probably wouldn't have sex at all.
My mission now is to just enjoy finding out as much as I can about the joys of sex - while ramming in as much (sadly vanilla) sex as I can before my biological clock takes my erection down.