Either you will learn that there is more room than you thought, or you won't. If there's a hymen there it will be more complicated, but it's still meant to let things in. Just let them in on your own terms, at your own pace.
My wife's ex was a "big" guy, and she only mentioned this to me while trying to reassure me that she likes having sex with me more. I don't believe her, though. Now all I can think about is how he was bigger than me and whether she misses that.
Just imagine telling her all the time how you can't stop comparing yourself to her ex, who is out of the picture, and anyway she loves you and would rather have sex with you. How does that sound? See? Now cut it out. She was telling you the truth, as you perfectly well know.
Don't forget to read Andrea at Carnal Nation.com.