"[Leaving] was inevitable," he said. "I could feel it."
The 25-year-old Duke product believes his departure from Cleveland was "distorted" because he decided against speaking publicly about the situation amid a flurry of rumors and speculation.
"I didn't feel the need to say anything because I knew the truth, and so did they," Irving said. "So it didn't matter what others said."
He added: "They didn't want me there."
In July, Brian Windhorst of ESPN.com reported Irving requested a trade because he wanted to "play in a situation where he can be more of a focal point and that he no longer wants to play alongside LeBron James."
MacMullan noted the Cavs front office started looking into trades involving the point guard in June, before his request was made.
Irving is enjoying a strong debut campaign in Boston with 24.8 points, 4.9 assists and 3.1 rebounds per game across 38 appearances. He ranks ninth in the league in player efficiency rating.
Now his Celtics (30-10) and James' Cavaliers (25-12) are two of the top three teams in the Eastern Conference and could end up on a postseason collision course.