3. Stella Kidd and Zach Torbett
It always felt like Stella Kidd (Miranda Rae Mayo) and Kelly Severide (Taylor Kinney) were going to end up together, given their electric chemistry. There were long stretches of the show in which they tried to make a go of relationships with other people, however, and Zach Torbett was one of these people.
Torbett (Daniel di Tommaso) was a Hazmat Specialist who worked for the city's fire department, and he and Kidd went on a handful of dates during season 6. They clicked in a multitude of ways, but like the relationship between Mills and Dawson, it was obvious that this was not the real deal.
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Torbett realized that Kidd was more interested in Severide than him, and things ended shortly after that.