To be fair I think it was slim pickings in there, Callum, fin, Luke t, Mike were all immediately off the menu, either due to previous couplings or they fancied someone else, which left naz or Luke m. Naz went for Eva, so really it was Luke or no one.
She was in to get into the villa, so obviously went with it, otherwise telling Luke she wasn't interested meant she was immediately out. So she was stuck between end her time immediately by being honest, or use him to get in.
Prob why she was a bit jealous about Callum and molly, not that she wanted Callum as such, more she wanted the air time and options.
I don't think molly is that into Callum either though, but she's playing the game. Likes him, but more like he liked shaugna. Just not enough. Think karma is going to bite Callum in the arse at some point. Whether in or out of the show, molly is going to do the exact same thing to him as he did to shaugna.