You can't give blood if you're a sexually active gay man but if your partner is a female-to-male transsexual legally male do the rules still apply?

If sexually active gay males can't give blood, I'm going to stop doing it. I'm not sure if they can or can't.
But in this situation, yes, the rules still apply just as much as they ever did.
However, this is an unenforceable rule. And a ridiculous one.
I would personally use 'don't ask don't tell', in other words, don't tell, and then you could give blood.

[In the UK if you're a man who has had anal sex with another man, even just once, even if you used a condom, they will prevent you from giving blood. This is apparently because of the increased HIV risk in sexually active gay men, because even though they test the blood thoroughly can still produce a false negative on tests and infect the person receiving the blood. Though apparently they don't discriminate against people who have had unprotected sex without being tested.]