Damn, that's a mouthful. You and your woman can have the greatest sex life in the world, and you will masturbate. Your woman can have 1001 different ways to get you off, and you will masturbate. You can be married to Tyra Banks, and you will masturbate.
Guys can, and do, get off in pretty much any situation.
Give them some tissues and five minutes of privacy, and they're all set. But women often see masturbation as something a little more intimate. Many women like to take long baths, turn down the lights, and yes, frequently, they like to use vibrators. If you're convinced she's being honest with you, then leave it alone. Let her have a vibrator, she's probably had it years before she was with you and doesn't want to part with an old friend.