Sure, she doesn't need to let go of them, but she will need to let go of the hope of ever realising them in practice. Japan might be okay with cousin marriages, but siblings marrying is too much even for Japan. On the other hand, Aqua loves Ruby as a sister, but that's it. He never loved Sarina (who Ruby used to be) as a woman. She was a really important patient who also taught a lot to Gorou, but that's it. Now he's taking as good care of Ruby as a sister as he can, within reason, due to being a responsible adult inside. He's no siscon, by far, in the traditional manga/anime sense. Ruby treats him exactly like a sister would, with full signs of the psychological mechanism that makes falling in love with siblings impossible, whatever it was called. So, no, I can't see anything much happening even if she learned the truth. You can't simply overwrite the past 16 years.