IT specialist Steve has been living with his girlfriend Carola for five years and wants it to stay that way forever. He is all the more disturbed when his friend and colleague Bob is left - out of the blue and for the much older Harald. When Steve meets the eloquent tantra teacher, he suddenly has doubts: could he face the same fate? How receptive is Carola to someone else's advances? A loyalty test, for which he hires Harald, triggers the highest level of alert in Steve. Before anyone else does, he decides to win his girlfriend over again as a preventive measure. With an ambitious fitness program, secret tantra courses and romantic ideas, he puts his heart and soul into it. Meanwhile, Carola doesn't recognize "her" Steve. Her single friend Anette, on the other hand, sees it as a typical male midlife crisis, which inevitably leads to a painful end to the relationship. Now Carola would like to take countermeasures - but unfortunately this comes across very differently with Steve: Her freshly bleached hair fits exactly into the fear scenario of her deeply insecure boyfriend. Now the crisis is really taking its course.