Well…sexual morality isn’t really a matter of laws. They’re a matter of morals. The Church can change her laws, but she can’t contradict her teachings.
but thats the issue, the church already has some contradictory doctrine. for example, the church says that sex must only be for reproduction, so ok then, if im lets say a billionare, and i can support many many women and children, then why cant i reproduce with many women? and why do i have to married? (and i know what your response will be) “because jesus said in the bible”, but have you ever stopped to consider, that jesus’s time was radically different than the time today. think about it, the reason Christ taught that there should only be one man and one women, was because back then the family was the only way a child could learn and be taken care of. back then they didnt have public education, state orphanages, a safe society like we do today. back then the only source of sustinence for a child was through his family. but nowadays the nuclear family is just not that necessary anymore.
(im not a heretic, im just thinking philosophically) that is why Christ in his infinite wisdom did not make marriage a dogma. whatever is not a dogma can be changed by the church. not to mention, the church has a few laws that jesus did not even talk about! for example, Christ never condemned the use of condoms or masturbation to my knowledge, (and yes, birth control did exist in his time)
and you mention “sexual morality”, well the church says that the purpose of sex is reproduction, you dont have to married to reproduce. i just think its a pointless rule, that makes many souls lose out on salvation. if sex laws were eased, i think about 75% of people who would originally be damned, would be saved.