Any of the full ship charters will be this way as apparently that is what their target demographic wants.
There are many gay groups that sail as a group on regular sailings. That won't be the party environment you want to avoid but it will be a standard sailing with families, kids, seniors, etc... I've done these group sailings before mainly because like you, I have no interest in a 24/7 gay party atmosphere.
Perhaps with growing numbers of aging Boomer and GenX gays, someone will realize there comes a point in life where that gay party atmosphere is no longer the attraction it was when you were twentysomething.
There may be a TA who can comment further on your options