Responses
I think it has a rather deep meaning than just "sleeping around", by that time "I" was aware he was not what by P wanted (so the sex was some sort of comforting both agreed on) and about the final confession it was something more meaningful as many have pointed out in the interpretations (which I'm lazy to resume sry).
That was because of a choice chosen by a complex emotion, and like what D said, only those who are directly involved can understand it and we as an outsider only can speculate why and why were those I love you's were said. ╥﹏╥
Am I the only one that can't sympathize with P, like he sleeps with E and then in the end he says he loves' I ' it kinda pisses me off