I hate this attitude you have towards "some young people". Are we supposed to assume that you have sufficiently grown up just because you make this comment? If not, you dont have any right to judge others. Now coming back to your question, if both consenting adults think that "some fairly disgusting .... acts" are the norm, when who are you to say other wise. In case one of the adults doesnt thinks so, they can move out of the relationship. If the society forces them somehow to stay together inspite of one of them wanting to move out, then you have arrived at a problem that you can try to solve.