You're absolutely right (and I think you've mentioned this before): the singling out of transhood by the law this way is disgraceful.

It would seem as if the trans characters in the fiction did the right thing at the right stage of the relationship. If they got away with having their paramour run off and puke, they're pretty fortunate despite the crushing damage to their self-esteem, and at least they didn't have to pay a grievous price to learn "well, definitely not that guy."