Daniel probably went to Jen's because of running into Abby. She mentioned JJ being all mopey, and seemed to be different now. In my opinion, it was a stupid move on his part. If he has to cover at work, then do so. Or (since we did not hear his phone or see him getting a text) was he faking having to go to work?
As far as Daniel/Nicole....they get together and she screws up in some way....but she does that with everyone. Nicole is Nicole. She means well, and when she has an idea, a hunch, she works on it. It may pan out, maybe not.
But it does seem that her choices in men expect her to be a combo of a saint and George Washington (I cannot tell a lie). In fact, they all feel she has to tell all, everything she thinks and does, but they don't. You know.....that old double standard.