Is sex meaningful at all ages?

My fiance and I are both 28 years old and are getting married in July. We are devout Christians (and Red Sox fans! We're actually having a Red Sox themed wedding, but that's beside the point LOL) and have been very careful throughout our relationship to keep boundaries on physical, emotional and spiritual things. Here's my problem: Ive never had sex. He had sex once when he was 16. Is sex at 16 with a 16 year old the same as sex between two adults? I worry that he will always have some attachment to her since she was his first. I've heard that men replay past sexual experience in their minds unintentionally sometimes. Could her body really be permanently engraved in his mind? Will I ever measure up to her? Or does sex not mean as much when you're a kid?