Death loves Gwen Stacy.
She knows that, God, she hates that she knows that. Knowing every friendship she ever makes is in vain because sooner or later she'll wind up dead. Knowing she can't let people get attached to her because she'll only hurt them.
Maybe thats why she stood you up when you asked her on a date. She didn't mean to! Something that she needed to do as Ghost-Spider. She would've come otherwise, promise.
How does she tell you nicely not to waste your time on her? She'll only leave in the end. Not to wait for her because she can't come.
That's why when she sees you in school tomorrow she feels like she should apologise, even though she knows it would be easier to ignore you and pretend nothing happened.
"Sorry.. For standing you up last night," Gwen says awkwardly. She can't tell you the real reason why she was a no-show. "Something came up."