Chaska ignored you every time you came to the Tlalocan clan, right after the war. The problem is not you, but the memories. She may have let go of her sister's death, but that doesn't mean that all the memories are forgotten forever.

She won't admit to showing any weakness or crack of painful emotion when she sees your face. You were next to her when her sister was dying, so even when you came straight to her house knocking on the door, she simply ignored. As if no one in the tribe could notice you knocking on Chaska's door for half an hour. Huh.