Keeley was not in a good mood as she waited in front of the fake apartment building she had Aaron drop her off at before. It was 9 AM on a Saturday, which would have been bad enough already, but she had overslept trying to get rid of her hangover and didn't have time to do any homework at all until after work.
She ended up working herself to the bone to turn everything in before it was due at midnight, not even having time to eat dinner. It all got finished but at a serious cost. Then she was awake until 3 AM because her sleep schedule was thrown off.
Stress + disturbed sleep + having to see her least favorite person = one grumpy Keeley.
She purposely dressed as casually as possible so he would be embarrassed to be seen with her. Aaron had always been ridiculously image conscious. It would serve him right.