Anyone with any experience with real relationships, real love, knows that penis size isn't the end all be all. My girlfriend and I are currently going through a "break" after 4 years and it's really tough. I have a bigger than average penis and the biggest she's ever had and also the first and only to give her vaginal orgasms. Our sex life was outstanding. It hasn't been too great lately which is more a result of other issues in our relationship. Granted, not having great sex or much sex at all lately has contributed to our problems, but it wasn't the crux of it. There are many other complicated issues. But the point is, she is seriously considering ending it with me and moving on. Now, is she still considering staying with me because of my dick? I seriously doubt it, but guess it could be a factor. To her at this point, I think my dick almost means nothing and she is perfectly capable of just starting over with another guy. As great as she thinks my dick is, many other things are much more important to her. I've learned first hand this obsession with dick size, even great sex, is much more of a guy thing. Women fall in love with the guy and how he can make her feel and how he can complete her life, not his dick, as much as we guys would love to think.
All that said, I'm sure in some casual sex instances, a big dick helps "complete" the package and the fun factor. And I agree that true "size queens" are either not looking for any sort of relationship or have other issues themselves.