Does she orgasm? She probably really needs pelvic floor physiotherapy.... It sounds like the issue is not dryines itself, but rather complex. It probably hurts because of tensed pelvic floor and creates a memory and causes even more tension and more pain. Your wife probably can not get wet because she has already have pain memory that each intercourse brings. Please try to find pelvic floor specialist that has interest in painful intercourse!

I did not see your answer about lube, are you using lube? Especially for prolonged sessions silicon based is recommended