In Jesus’s mind, to answer the divorce question necessitates a right understanding of marriage, and to get at the nature of marriage one must go back to the beginning, where we see God instituting marriage as the lifelong union of a man and a woman.
yes, but that's because there were no homosexual marriages/positive homosexual relationships at this time in history, only homosexual temple prostitutes, so for Jesus to bring up homosexuality in a marriage debate would just confuse those he's trying to teach about the question at hand--which is about divorce.
