Sex, like kissing, is a different form of commitment.

Everyone has different triggers and fears.

Ask yourself what the act triggers in you?
Why couldn't you handle it?

What fears does it release?
getting pregnant, dieseases, re-living your rape? What?
Getting to the root cause will help you accept the act when
you find your lifemate. Mate being a key word here.

Do you fantasize about having sex? About making love?
(Yes, I argue they can be two different things.)

And let's be honest. It's okay if you don't fantasize about
those things. You might not want to have sex or
make love again, ever. It's your body and your choice.

For years I was a very non-sexual person - kissing was cool,
groping was out. Even my fantasies, though quite submissive
and naughty didn't revolve around the act of physical sex.

The right man changed all that for me and I kept him.
Perhaps you haven't met the right guy or gal yet.

As to your concern about being "tight", most men don't have
the monster cocks we see in photos. Lots of lube and patience
will get you through your first couple of sessions with your partner
and the more you relax, the better it is. Practicing with a dildo or
vibrator is a fun way to get over that fear.

Big hugs and I hope you've found some more answers that help.