(CNN) -- The man who says he was behind the Manti Te'o girlfriend hoax claims he was in love with the Notre Dame linebacker, but the athlete knew nothing about the ruse.

"He had no idea," said 22-year-old Ronaiah Tuiasosopo in the first segment of a two-part interview that aired Thursday on "Dr. Phil." The second part is scheduled to air Friday. "He did not know anything."

Tuiasosopo told host Phil McGraw that he had romantic feelings for the football player. Asked whether he is gay, he said, "I would say, yeah, I am gay, but honestly, I am so confused, I'm so lost."

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In the interview, Tuiasosopo says the charade was so difficult to maintain that he tried to put an end to it several times, but it didn't work.

"There are many times where Manti and Lennay had broken up. But something would bring them back together whether it was something going on in his life or Lennay's life, in this case in my life," Tuiasosopo said.

He added, "I wanted to end it because after everything I had gone through I wanted to move on with my life. Me, Ronaiah, I had to just start living and let this go."

Finally, after learning that Te'o had Skyped with several of his former girlfriends, Tuiasosopo essentially killed off Lennay Kekua -- the character he had created -- having her die of leukemia.

A love story unravels

Thursday's segment is the latest revelation in what began as a story of one of the nation's best college football players leading his team to victory hours after learning his girlfriend had died of leukemia, a story later dismissed as a hoax after it was revealed Kekua did not exist.

Sports website Deadspin broke the story this month that the girlfriend whom Te'o, this year's Heisman Trophy runner-up, had talked about and had claimed died in September of leukemia wasn't real.

Te'o rose to national prominence leading Notre Dame's Fighting Irish to an undefeated regular season. As he and his team excelled, Te'o told interviewers in September and October that his grandmother and girlfriend, whom he described as a 22-year-old Stanford University student, had died within hours of each other.

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"I miss 'em, but I know that I'll see them again one day," he said then.

An online relationship

In the weeks since news of the hoax broke, Te'o said the relationship was carried out via e-mail and telephone.

Last week, Te'o told Katie Couricthat Tuiasosopo called him the day the story broke to confess.

During that interview, Te'o said he doubted the voice he knew as Kekua belonged to that of a man.

Tuiasosopo has said he faked his voice to sound feminine. In the interview, he was repeatedly challenged by the talk show host to prove it.

Tuiasosopo' s state of mind

Psychotherapist Robi Ludwig said the behavior described by Tuiasosopo to McGraw is very possible.

"We see this with Internet dating. Sometimes people lie," Ludwig said on CNN's "Erin Burnett Outfront."

"It's a place where they can experiment and where they can impersonate the other sex."

Ludwig said it is possible that Tuiasosopo "actually did have a crush on Manti Te'o and was confused about his sexuality."

"And the reason why he impersonated this woman was to see what it would feel like to be intimate with Manti Te'o to be loved by Manti Te'o," she said.

"Who would say this if it weren't true? I don't get the sense that he's a sociopath. I get the sense that he's confused."

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