It is hard to answer such a question about a stranger. However, since
you ask it, I searched for a clue to Andre Rieu's sexual orientation.
In 1999, the Advocate, a magazine focused on gay and lesbian issues,
wrote an article about gays and lesbians in the classical music world.
Apparently, there are few contemporary classical musicians who are
'out of the closet'.
Because of that finding, I suspected that I would have a hard time
finding out anything about Andre Rieu. However, on his web page,
Andre Rieu describes a close relationship with his wife in his
biosketch. And, in a biography written by a GA researcher, it was
noted that he has two sons.
Biography of Andre Rieu by a Google Answers researcher:
Andre Rieu's biosketch:
This implies strongly that Andre Rieu is not gay. Perhaps he is
bisexual, but other evidence would have to be found.
I hope that answers your question.