Ok so according to Joseph after 4x16 he is expecting some hate-mail, and he mentioned this in relation to klaroline. Now we know that 4x16 is the klefaroline episode and then he said that 4x18 is a must watch for the klaroline fans.
So I’m calling it; klefan have sex in 4x16, Caroline gets jealous. 4x17 and half of 4x18 They make up then all three of them have sex in 4x18.
They never said Klaus was getting laid only once.