Joanna returns in full on breakdown mode. It seemed as if everyone was confused as to whether she was mad at Romain (for the Adriana flirting?) or something else altogether. After a some tears and shouting we learn that it's because Marta's DJ ex is at the club. Ohhh!
So Joanna let's out a stream of tears (she's got one of those lilty crying voices) and Romain just packs it in and goes home. Probably not how he expected to spend his big night.
And then Marta, who earlier bemoaned the fact that Joanna doesn't defend her, blows up at Joanna for, well, defending her. Yes, she was mad about her causing a big scene, but still, it's quite a tangled web between these three.
Prediction: Marta's got to move out or Romain and Joanna may need to reevaluate their relationship. Something's going to give here.