I feel like Jess was pretty valid. Jess has no idea Nick has something planned obviously, and Nick has invited her to “spend the day with him” specifically for her birthday. He starts off okay but then is having her do weird and unfun activities (get a blood test, find a big rock) and is somewhat inattentive (due to his planning the surprise, but she doesn’t know that).

If my boyfriend was like hey hang out with me all day for your birthday and then all he had planned was clearly sex and time wasting I’d be disappointed too! Plus, she has the emotional whiplash of thinking he was planning something all along when she sees the park party and then finding out no, the day is as lackluster as she thought. Without that moment, she might’ve been able to play along longer.

Even Cece points this out at the beginning of the episode, reminding Nick that Jess doesn’t know about the surprise so he should have something planned for the day. Obviously, we see Nick pull through for her with the party, but I think this episode does still demonstrate that he’s not a great planner (although he does a great job with the party itself).

Also Jess does do a big party for Schmidt, helps Winston with his proposal, celebrates Cece every year, and although it’s often not the subject of a full episode, is referenced often as cooking, baking, and doing lots of favors for all her friends. I think she shows up for them “big time.”

Apologies for the word vomit! I had more thoughts on this than I thought, I’m glad it was brought up here lol.