To me, pressurising someone in this way is abhorrent. Saying a consensual sexual choice is wrong seems destructive. We need more loving relationships in the world, not fewer.
The degree to which sexuality is mutable is hard to figure. A very close friend of mine married a woman who had lived all her life until she met him as a lesbian. The vibes I get - as always I could be wrong - but the vibes I get are that she is happy and unconflicted. The difference of course is that this is something that occurred in her life naturally, not because she thought being gay was Evil.
We all make lots of sexual choices - the physical types we like, the practices we enjoy best. Some of these seem mutable, and some immutable. Some which seem fixed then change unexpectedly. Sometimes that blows your life apart. I always feel my sexuality is quite mutable (*). But then my feelings in general not just sexually tend to be changeable and chaotic. I accept that for other people things are more stable, for good or bad.
But even silly things like fashion can change the things that people like or try. Even horrendous things like the sexualisation of foot-binding come and go.
So, sexuality: invincibly strong, but fragile: irresistable but sometimes mutable. And not a suitable area for condemning others, or feeling too proud of being supposedly 'normal'.
(*) though of course I am in steady relationship, which isn't mutable