Dennis departed the Middle Eastern team in September over a reported equipment dispute, before completing a "dream move" to Team Ineos on a two-year-deal.
And though the 29-year-old had initially kept a low profile on the split, a recent interview with new teammates Geraint Thomas and Luke Rowe has since revealed all.
"In the end, it just wasn’t good for me to be there," Dennis said on the Watts Occurring podcast.
"I was struggling mentally and in the end, it was affecting home life. It was only going to get worse so I just decided on what was best for my family.
"There were more things behind the scenes going on but it got to the point where... I wouldn’t go to the point of being absolutely depressed but if I didn’t pull out right there and then it would have probably turned bad."
Having walked out on Bahrain-Merida on the eve of the Tour de France time trial in July, Dennis admitted he "probably read into the sh*t online" too much and left himself in "a bit of a mental battle" as a result.
"I wanted to know what was going on and where I stood in the cycling community," he said.
"At first, I laughed about a lot of the stuff... journos... everything. I couldn’t fight back because it was all about keeping quiet. We agreed on keeping quiet and sorting it out behind closed doors but a few things got out."
Despite his aforementioned difficulties, Dennis still managed to retain his time trial title at the World Championships in Yorkshire and now sees Team Ineos as his best chance at continued success.
"It’s the place that I think will best support my Olympic and time trial aspirations," he added.