PG-13 for or adult themes, since "The Lady with the Dog" is about an adulterous affair. On the one hand, we don't get to see any actual sex here; Chekhov glosses over the physical act in Yalta with cerebral meanderings. On the other hand, there are those cerebral meanderings to consider. Chekhov shows us the sex from an intellectual, emotional, analytical perspective, if not from a physical one, when Gurov considers the ways his various women have reacted to his various affairs. What we mean is:
From the past he preserved memories of careless, good-natured women, who loved cheerfully and were grateful to him for the happiness he gave them, however brief it might be; and of women like his wife who loved without any genuine feeling, with superfluous phrases, affectedly, hysterically, with an expression that suggested that it was not love nor passion, but something more significant; and of two or three others, very beautiful, cold women, on whose faces he had caught a glimpse of a rapacious expression – an obstinate desire to snatch from life more than it could give, and these were capricious, unreflecting, domineering, unintelligent women not in their first youth, and when Gurov grew cold to them their beauty excited his hatred, and the lace on their linen seemed to him like scales.(2.9)
We then get, in comparison, Anna's own reaction, also known as "the diffidence, the angularity of inexperienced youth, an awkward feeling" (2.10).