It looks like you put the bra next to her shoes for the seconds photo... For a second I though you got a candid snap of just her lingerie and her heels. This would have been insanely hot as it suggests that she had been actually walking around in just her bra, thong and heels rather than simply getting undressed all at once after a night out!
Well then, that changes everything!!! You need to give us some more back story, we don't know who you are, where you live, or who this person is so feel free to tell only us about the situation around the panties in question whilst still being able to maintain your anonymity
Ok I will give a little more info on her. I know her and her roomate (a guy) so I am over at there place pretty often and I can occasionally sneak into her room from time to time.
She is late 20s, in pretty good shape (runs a lot), and she is really nice and seems like a good girl type, but I have seen quite a few guys flirt with her before so I always wonder if she has another side to. She has a BF but I know for a fact he wasn't with her the night she was wearing that red thong. She was out with her friends for a girls night out. Which is why I thought it was so fucking hot she chose to wear a tiny thong with a matching bra and high heels!