With Alonso returning to McLaren seven years after that split, Dennis admitted questions over team harmony were inevitable, but said different approaches and a wider culture change would ensure past mistakes will not be repeated.
"I know the media will be looking for any kind of fracture in any part of the team's relationship, especially between Fernando and I, to immediately get a wedge in," Dennis reflected. "But I can tell you, they'll be wasting their time.
"The reality is that in F1 seven weeks is a lifetime; seven years is just a huge amount of time. You continue to mature - I have mellowed quite a bit, and I'm much more inclusive.
"If you go back to that period [2007], if you look at who struck the first blow, I would say Lewis [Hamilton] had his role to play in starting this process which then escalated. This one got away from me. Could I have engineered a way out of it? I could have probably done things better. You regret the mistakes you make in life.
"Of course when we [Dennis and Alonso] started to meet over the last few months, no question there was a bit of circling and discomfort, but there is a friendship that we have re-established. You would be very suspicious of it, or wouldn't think it had any grounds, but we are now focused on the future.
"We have to succeed together, and we both agree that the core ingredient is to be happy, because the opposite is rubbish. So we will absolutely have our radar on and avoid anything that can escalate in our relationship. I don't anticipate any issues."
Alonso echoed Dennis's sentiments, saying that the disappointment of how the 2007 season evolved was a fundamental part of his desire to rejoin the team.
"I am happy with everything I have done apart from 2007," the Spaniard said of his F1 career. "I didn't achieve, didn't deliver, the best of myself.
"So now seven years later [I am] more mature - you learn things and understand things probably you didn't at 25 years old. Now I arrive to finish this job I started in 2007. This was the first priority to come back.
"I am sitting here, ready for this challenge with McLaren-Honda, because I see no problems at all."