Imagine you're in a fantastically happy monogamous long-term relationship; your SO is, as far as you're concerned, the one and only for you, and they feel the same way about you. The only fly is the ointment is SO's best friend, who has always been a bit "off" with you; you've never argued, there's no particular reason you can pin down, you just figure they don't like you. Then one day, So's BF takes you aside, asks you to say nothing to your SO, and confesses deep passionate feelings for you; they idolise you and will love you forever. How would you feel about this revelation? How would you respond?