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Bruce Jenner's high school girlfriend Michelle Rosenthal speaks out about his gender transition in a new interview with Inside Edition, airing on Thursday, April 23. In a preview clip, Michelle says she was surprised when hearing the news that Bruce would be coming out as a transgender.

"I would have never thought that in a million years from knowing him from high school," she shares, "When it came out in the papers that he was thinking of this, I think everybody was really shocked." Michelle, however, shows her support for Bruce. "I hope he figures out what it is that he would like for his life. I hope that he finds happiness and that he is in that."

Michelle also recalls her prom date with Bruce. "We danced close. We did kiss. He seemed to enjoy it," she recalls. Talking about Bruce's personality on "Keeping Up with the Kardashians", she says, "I don't know, he just definitely doesn't seem like the same Bruce."

"The Bruce I remember was happy-go-lucky. Nice guy, friendly with everybody, popular. The few times I've seen him on the TV show, he just didn't look happy," she adds.

Bruce's interview with Diane Sawyer, in which he will discuss his transition plans, will air on Friday, April 24.