A.E.
My cousin went through a similar phase, she's 7 now. She had a male teacher at her daycare and she looovveed him. I thought it was cute and harmless. He never did anything to promote her fascination, he was just fun and he played with the kids like most men do (i.e. tickling, throwing in the air...all that stuff that makes us mothers nervous, but that our kids LOVE) She eventually moved on to another little boy in her class and he was her boyfriend for awhile. For her, it meant that he was her best friend that was a boy. He was the one boy she wanted to invite to her house to play or invite to her bday party and he was the only boy she actually hugged (no cooties I guess). I don't think they understand what they're saying when they refer to a boy as their "boyfriend."