If my best friend was a girl? Happily accept. (Or, if she's one of the multiple female friends I have who is engaged, married, or an ex-girlfriend of mine, decline and have a long talk with her.)

If it was my male best friend? Decline but tell him I'm fine with his decision and am glad he has such faith in me as a friend to confide in me.

What would you do if you were single and Valentine's Day was approaching?