Also Dexter technically did not cheat on Rita to begin with.. if you remember, Rita broke up with Dexter and said she didn’t want to see him, that he was just like her ex husband (who was a drug addict, and she thought Dexter was on drugs also).. It was then later on in the night that Dexter and Lila had sex, almost directly as a result of his and Rita’s break up. If they hadn’t broken up, I doubt he and Lila would have ever been sexually involved. Almost immediately after, Dexter got a voicemail from Rita saying she was sorry and she wants to work things out between them. I have not watched that season for a long time, so I can’t recall exactly what goes on in Dexter and Lila’s relationship afterwards, pretty sure they still had sexual encounters, but it went very sour after he became involved with Rita again. Damn I miss Rita though, she was such a good character and balanced. It is very hard for me to like female characters, I hate almost all of them. Don’t even get me started on Deb.