In The Great Gatsby, what is Fitzgerald's purpose in having Jordan phone Nick the morning after Myrtle's death?
The evening Myrtle is killed, Nick and Jordan return with Tom to his house. Jordan very much wants Nick to come in with them but Nick won't, even when she presses him by saying it's only 9:30 in the evening. Her need for him, as she is apparently shaken by Myrtle's death, is a contrast to her usually cool, self-possessed self. Yet he can't respond to her emotionally in the way she would like: he says he's sick of them all, including Jordan.
When Jordan calls Nick the next day, she says he wasn't very nice to her the night before. She wants them to get together, presumably to talk things over. She is reaching out, trying to communicate with Nick. She even offers to come into the city. He refuses to see her, and this refusal marks the end of their relationship. Nick's disdain for her at this point couldn't be more evident: he says he didn't "know which of us hung up with a sharp click," but "didn't care." He says "I couldn't have talked to her across a tea-table that day if I never talked to her again in this world." Instead, he tries to call Gatsby a few minutes later and attempts to reach him four times.
Nick is more emotionally concerned about Gatsby at this point and is sick of Jordan. With the phone call from Jordan, Fitzgerald signals to the reader that Nick's relationship with Jordan is over.