@CFC, I'm not convinced. If you were lost on a desert island with someone of the opposite sex, I think you'd eventually get over it. I've met people who say they couldn't ever bring themselves to eat raw fish, but - again - if you're starving, you will eat it and like it.
The word trauma gets thrown around a bit too much.
A lot of straight guys I've met insist that it's traumatic to catch a glimpse of gay porn or even see someone's dick up close. That's silly. It's not "traumatic". They're just being snowflakes.
When straight guys go overboard about how traumatic cocks are, it always makes me think of Lady Macbeth and how the lady doth protest too much.
Gay guys, similarly, can be so afraid of their heterosexual side that they claim it is impossible. It's not impossible. It's not traumatic. It's just a vagina.
Fucking a woman in the ass isn't that different to fucking a man in the ass. Having your dick sucked by a man is no different to having your dick sucked by a woman.
There's no such thing as a hard-line heterosexual/homosexual. Sexuality is a construct. It doesn't exist.