Tigerstar and Sasha were mates. Tigerstar first met Sasha and taught her how to hunt and saved her from foxes. He later asked her to join ShadowClan, to which she declined. Sasha gave birth to his three kits, Hawk, Moth and Tadpole. Tadpole later drowned. Russetfur delivered the news to Sasha that Tigerstar was dead. She took her remaining kits to RiverClan. Sasha refused to stay in RiverClan because she felt the safest place for her kits was away from her. Tigerstar came to Sasha in a dream saying that Tadpole was safe, but not with him (most likely because Tigerstar resides in the Dark Forest).
Erin Hunter confirmed that Sasha was Tigerstar's true love, not Goldenflower.