I think they are very sweet together, but that is just my opinion.
Maybe they were taking it slow and steady rather than dry humping each other every second the camera is on them?
Maybe she doesn't like being filmed being affectionate and he is respecting her feelings?
Or perhaps he has realised you don't have to stick your tongue down your partners throat when the camera is on you.
We don't know.
And being relaxed and friends with each other is part of building a long term relationship that lasts.
I agree badcat, i actually find this makes things far more believable then if he was sticking his tongue down her throat every five seconds