The truth was that Lydia didn't know if she could trust him to deal with it. She had spent exactly one night with him and two afternoons up to this point and they'd both been otherwise engaged with training or working or with other people otherwise. There was no way for her to gauge it beyond the gut feeling that she had, telling her that this was going to end badly. ...and she couldn't trust that, either, because her hormones were all out of whack.
Sighing softly, rubbed at her forehead and ran her fingers through her hair. "Maybe we should sleep on it," she said. "I don't know what I think about anything anymore, Finnick, I haven't been able to think straight for two days." Her lips pressed together in thought and her eyes were cast down. "...maybe tonight is not a good night for this. I should probably go..."
Where she was supposed to go, Lydia hadn't decided yet, because the last place she wanted to be right now was exactly where she was in this position and the second to last place was anywhere near Stiles, because she couldn't fake it with him. When she was upset, he knew it, and he'd press her to talk about it; not something she was in the mood for doing.