That seems like bad advice. Your preferences are what they are. "Giving advice on how to become bisexual, or polyamorous" seems just as bad as "giving advice on how to become heterosexual, or monogamous."

Why? That might make sense if a preference is part of a terminal value. But if it isn't this may not be that different than advice on say how to enjoy eating healthy foods (in my own case the answer for spinach was eat it frequently with tasty cheese). For that matter, there might well be circumstances where it would make sense to try to adjust one's preferences to becoming closer to monogamous (say one is dating someone who is strongly monogamous).