She definitely has a boyfriend. She calls him her "sister" but of course we already know it's her boyfriend even before Calum actually said "you have a boyfriend" two or 3 times tonight.
Calum I'm not so sure about him having a girlfriend. Tonight when Cami said "you have a 'brother' and he said "yeah but", she pounced on the fact he said yeah and was like, "oh, so you
do have a brother you said yeah", so it seems before that point Calum was saying to her he was single.
He then went on to backtrack by saying that he has someone that is "on his mind", so that does not necessary mean it's a girlfriend. I know some of the girls told Katie P when she entered that Calum had a girlfriend, but he seems to be saying something different himself. It could be just a girl he's casually seeing or something but not an actual girlfriend?
Cami seems to definitely have a boyfriend though so I think he was telling to ease off a bit.
I could still see this pair hooking up in there though if Calum got drunk enough.