@Qx403
They've had a sexual relationship ever since Chapter 5 (when the male lead pins her down and gives her a hickey.) We've never seen them have sex, but it's super obvious in hindsight that most of the jokes in the series are based around the female lead intentionally teasing the male lead with how their relationship is so different from when they were kids, not making unintentional double-entendres.
She bought a porn PPV card to watch porn with the male lead, they had sex and then they played UNO (by themselves and with the realtor/her GF.) The joke is that her friend thinks all four of them had sex all night, not that they didn't do anything sexual.