According to Jim Season 1 Episode 16

After Jim is diagnosed with high blood pressure, Cheryl decides to do everything to help him. She makes him special food, give him backrubs, and keeps asking about his day in order to free him from stress. But Jim doesn’t know how to share so much and tells her an old financial problem of the firm. Cheryl stays up all night doing math to figure out a way out of the problem. Jim says she has a disease and is always trying to help people, which Cheryl responds with stop caring about him. In the end, they finally settle their issues when Jim says he loves her and would be a total mess without her.