Elsa was really close with Jack, while they grew up, their friends teased them all the time saying they liked each other and making kissing faces when they were together. Eventually they did start to have feelings for one another and everyone could see it in their glances, smiles and blushes, but they wouldn't admit it to anyone, including themselves.
When they were 14 they kind of dated for a while secretly but it was really hard between Jack's Ice Hockey practices and Elsa's figure skating so, one day Jack asked Elsa to come over to his house so they could talk, Mr and Mrs Arendelle were out and Anna was at Rapunzel's house so she went to Jack's, eager to have some time with him. When she got there Jack was waiting for her in his front yard, he was wearing a baby blue polo and some brown khakis that suited him very well, Elsa hadn't seen him in about 3 weeks and she thought he looked as handsome as ever. She ran to him and tackled him with a hug, one that he did not return. Elsa noticed the lack of movement from him and quickly scanned his face with her icy blue eyes for an answer to which he replied with ''Elsa… we seriously need to talk, I think this umm 'us' thing isn't working out, we barely see each other and our schedules are so booked up, I don't think we can keep this up, I really hope we can still be friends cause that's what we are… best friends, and I really don't want to lose that friendship you know''
Elsa was shocked to say the least, she couldn't believe what she was hearing, she loved Jack, she trusted him with her feelings, her stories, her secrets, more than she had ever trusted anyone with anything about herself before.
Jack could see the hurt in her eyes so he decided to speak ''Elsa please say something, anything, please I want to know what you have to say''
Elsa ignored him, she was absorbing the pain of every word he had said, the words were piercing her like shards of glass, she turned around, tears forming in her eyes, and began running back to her home.
''Elsa!'' Jack called as he started running after her.
When he got to her house he noticed there were police patrols parked at her driveway, Elsa was sitting on her door step with her hands on her face, sobbing uncontrollably, the policeman on her side was trying to comfort her but it didn't seem as if it were helping at all. Jack didn't want to interrupt them so he turned around back to his house.
Later he found out from Rapunzel, that was with Anna when she got the news, that their parents had been in a fatal car accident and had passed away.