No one could compete with the object of Lady Sif's affection. If there was a fault that stood out so starkly amongst her other faults, Loki would firstly point out her blind devotion that made a hound's seem childish. Sif never did anything by halves and her loyalty was an extreme case for her. Whatever she loved, respected and protected was done so in such a strand of severity that it was both inspiring and frightening.
No suitor would ever win her over.
Lady Sif had been in love since she was just a girl with long golden hair, before she'd ever wielded a blade. It was the same reason Loki had childishly changed her hair color, and had been unable to change it back.
She had not cared, other than tossing him in a pond with giant fish that had only looked curiously at him with wide bulbous eyes.
She still did not care, for any comment Fandral may have about her beauty, how her mother wished her to marry or how Frigga and Odin had told her what a good, just ruler she would make.
Not even Thor, golden and perfect Thor, could match to her devotion.
Sif wore blinders, only allowing her to see what hung the stars and placed the cosmos into existence. She would never, ever be seen seeing someone else, someone who would love her back.
Loki could not claim to total apathy over it, but it was such a waste because Sif – beautiful, bold, fearless, loyal Sif – deserved so much more than giving her body and heart over for such an unworthy cause.
Lady Sif would never love a man, not when her blade sang so sweetly when it cut through the air, or when her beloved spear pierced the sky, or when the sharp retort of her bowstring snapped back so lovingly. Sif would never love a man so much as she loved the call of war.
And Loki, for all his tricks, could not compete with such a suitor so finely attuned to the Lady Sif.