[Dottore]

Well, you've come to the right place.

First, don't take this personally.

For me (and a lot of men I know) sexual attraction is completely visceral/chemical thing. I have had good female friends all of my life. Many have been attractive. But if the chemical attraction wasn't there—I always tried to ensure the relationship went no further because I knew this could only end in grief. This could be happening in your case.

Unlike women, guys usually know right away whether the woman is someone they want to bed—and if they don't, then remaining friends is far preferable.

Women's feelings tend to evolve. You might meet a guy, but not be really attracted to him until you've spoken to him and spent some time with him. This is not the case with men. We are much shallower.

Of course, all that said, your friend could be gay, or have commitment issues or performance fears or a mother complex or any of a thousand other issues.

Good luck.