Straight and lesbian romantic and sexual relations play substantial roles in the story lines. A gay man makes mildly lustful comments and observations. In Season 3, his relationships play a role; men are shown kissing men.
Making out occurs regularly; we see breasts fondled (over bras only) a few times, and many episodes show kissing and cuddling in bed leading up to sex that is mainly implied. Sex is only seen very briefly a few times, typically with one person totally under the covers and without exaggerated movement.
The only nudity in the first two seasons is a split-second view of a woman's breast when she flashes a man. Women are seen in bras occasionally, in panties less often; male nudity is never seen.
An extramarital affair decades ago is key to an on-going story line. Sexual coercion by powerful people is key in one episode.
In one scene, a woman and man are walking by a river at night. The woman takes off her dress and runs away playfully before the man catches and covers her up. (Deleted. Personal opinions about content are not appropriate for the Parents Guide.)