if a lesbian is attracted to someone who was raised as a woman and living as a woman when they met, and that person then began to take male hormones and start masculinizing, then that would not change the lesbian's core identity. this is a special case to have a partner to transition to the other sex while in a relationship to them.
the same goes for a straight woman meeting someone she believes to be a man only for them to correct their body to female. That woman would then have to wrestle with whether to stay in the relationship or not, or if that makes her a lesbian.
now, being attracted to someone right from the start knowing they are a ts, that is different. of course, there are 2 paths here. one is that the person is attracted to ts's. the other is that they fully accept the other person as the gender they believe they are and present. so if a lesbian ignores the ts part of the person who is living as a man and is seeking (or has had) surgical correction, then yes, this would be a heterosexual relationship. So the lesbian might really be a bisexual, or the lesbian is making an exception since the transman knew what it was like to be raised as a girl and is more likely than most other men to know how important it is to be tolerant.
as for the transguy, if he is attracted to the lesbian as a straight man, then he would still be a straight man. your orientation is determined by your perception of the relationship, not the other person's. if the lesbian wants to deny that this is a straight relationship, then the transman can still regard it as a straight relationship. if the lesbian has to loophole it in her mind to make it work, the transman is not obligated to play that game.
personally i'd question any "lesbian" that's attracted to a post-t, post-top surgery trans man. to me that sounds more like bisexual, not lesbian.
