So how do Clavell and Olivia act once they are a couple?
It depends a little on what point they are at in the relationship
See, their relationship started between "Clive" and Olivia, against all Clavell's good judgement. Olivia, ofc, saw right through his disguise but still enjoyed teasing him, and this teasing eventually turned serious. And Clive... he couldn't deny it was fun. Responding to her teasing was innocent and he knew he could back out at any time. But just like her, he eventually realized that a line had unintentionally been crossed.
Their dates were very typical. Holding hands, going out to eat, talking about school. But ofc, there was always a level of guilt for Clive, for the deception.
When he revealed the truth Olivia just kissed him and ran her hands through his hair. She always wanted to do that.
As Clavell, their relationship is... softer. More romantic. With Clive there was the energy of a school romance, but with Clavell they are more of an established couple. Clavell cooks breakfast for her when she stays over, she takes Houndoom for walkies, there's more home-cooked dinners. They still hold hands.
There's still a certain level of guilt for Clavell though, on account of her still being a student. But that's just because I enjoy the drama...
Then ofc there's the sex which is awesome