Why did she lie to me? What should I do?

So I skype with this girl who lives all the way in Australia and after the first week I was lovestruck. We skyped every day and before anybody asks, I know we aren’t in a relationship at this point and never will be because we live so far away from each other, but she’s coming to where I live in December (unrelated). Anyway, earlier today I asked her how the party she went to the night before was and then I asked if she hooked up with anybody. She said no. Few hours later she gets tagged on facebook in a photo of her making out with another guy and I went wtf. At this point it’s pretty obvious that I like her. Anyway, my question is why did she lie to me? To preserve my feelings? She knows I like her but I would have preferred that she tell me the truth instead of lying to me straight up… And my second question is, what should I do about it? Ask her why she lied to me? I’m just a little confused as to where to go from here because it’s going to be really awkward now. And I know that we’re not in a relationship.