The Five-Year Engagement star said that relationships often change and that anything can happen in life when it comes to romance.
"I don't [believe in 'The One']. I think relationships are an effort and it's about timing, an actual decision, and two people deciding they will be the best person for one another," Segel explained to Parade.
"And what happens if you miss the one or they die? Now you are doomed to a life of loneliness? We know that's not true. I think you want your partner to be your best friend. Even attraction will change. But what everyone's looking for is a partner in crime."
Segel also confessed his reasons behind choosing to remain single, adding: "I don't want to have a girlfriend for the sake of having a girlfriend. I have no desire to pick a random girl. I want the right girl. There are plenty of opportunities, but I would rather have the right one."
He recently spoke out against the big egos of many Hollywood actors, vowing that he would never become a "jerk".
Watch Jason Segel in the trailer for The Five-Year Engagement below: