Adams, 36, said he decided to walk away from the show halfway through filming season seven.
"As we were starting to talk about renegotiating contracts, I took a moment," Adams told THR.
"Everybody was going full steam ahead and I stopped and said, 'We need to think about this because this is more of my time and more of my life — and what's the story left to tell?'
"When I looked at the work I was doing, Mike would become a full-fledged, certified, legal on paper lawyer. That's a long way from when we met him and he was this brilliant burnout pothead with no real prospects. I thought we'd come so far and now Mike is going to work to be a lawyer and he's engaged to the woman of his dreams and he's got the means and opportunity to do whatever he can imagine.
"I had this voice in my head that said that we've told his story and if he hangs out longer, Mike is just going to be another lawyer on television. That didn't feel right for him."
Adams said that he and Markle, who is leaving the show due to her upcoming wedding to Prince Harry, had a ball filming their final scenes together.
"There was this natural sense that we both knew that the time had come for both of us," he said.
"It went unspoken and we just enjoyed the hell out of the last few episodes that we got to shoot. We both knew that we wouldn't be coming back. It made every one of our scenes that much more special. We had a great time."
Adams wouldn't reveal whether or not his Mike and Rachel will have a fairytale wedding at the end of season seven, but hinted that fans should be happy with their final storylines.
"It just so happens that the timing of how I was feeling [about leaving] and what was going on in Meghan's life created an opportunity where there was no need to force some conflict or tear Mike and Rachel apart," he said.
"It allowed us to go on to whatever happens next for Mike and Rachel together."
As for what's next, Adams is going to take a break before investigating working behind the camera for a change.
"After seven years on this show, I feel really empowered and capable of taking on more of a leadership role and getting things made," he said.
And he hasn't ruled out a return to Suits at some stage in the future.
"If it felt like it was the appropriate thing to bring Mike back for a big goodbye, then that's something I could be open to," he said.
The second half of season seven will start airing on Foxtel's Universal Channel in March.