I've never been one of those people that day-dreamed about being married to one person for the rest of my life, due in some parts to my polyamorous heart and in other parts to my fear of accidentally tying myself to a person who then decides that neither of us can have sex or fall in love with any one else "so long as we both shall" suffer in miserable silence.
So why does marriage equality matter to me in any way?
Because it's a matter of civil rights? Well, duh, although it saddens me to realize how many "equal peoples" turn a blind eye to that fact. But that's not why it really MEANS something to me, why it personally affects my own selfish little reality.
True marriage equality matters to me because I am FtM transgender with enough general legal knowledge to know that, at some point, marrying one of my companions may be the only way to protect and care for him/her. But my birth certificate will always declare me a 'legal' female, making any potential marriage to a female love a "same-sex marriage."
And yet, as a transitioned male, if I attempted to wed a male love, those who would denounce equal marriage rights would deny us the opportunity because I 'chose to be a guy'.
So, yeah, same-sex marriage rights directly affect me even though I have no active interest or intentions to tie any knots with any gender.
Also, there's that little softie inside me that just genuinely enjoys seeing other people be happy, and love is number one leading cause of happiness.