My theory: everyone's saying it's a guy. I could see it being a girl who actually liked OP, but probably gave him pictures of someone else because she's insecure of how she looks because of some reason or another. She probably hoped to make OP care about her through her personality alone, so that way when she did finally show OP the real her, OP wouldn't care and would still like her. She probably thought she was ready for that and reluctantly agreed to have him come to Florida, but when OP actually arrived she panicked and decided to ghost him. Now the only way she can see getting herself out of this situation without accepting blame is to lie and cast OP as the bad guy.

But like I said, this is just my theory. It could just as easily be a dude.