Here's the explanation - women follow their feelings. At some point she was feeling horny and that's why she was touching/kissing you, but by the end of the night she didn't feel horny enough to go home with you and so she didn't. Women are 100% selfish and about what they want. As for the rest - the excuses, saying she's "busy" and the bull**** about being ill. That all shows low interest. Maybe she thought she'd give you a chance when another option fell through, but in the end she decided she didn't like you enough to bang you.