I imagine one might take a sweater from a potential significant other, or unknitting that sweater. Of course, this could just result in a restraining order and jailtime for sweater-related thievery and destruction.
knit hats! scarves! gloves! cover them in knitting – if they can’t move, they can’t escape
(there actually is some knitting superstition for that! you’re supposed to knit some strands of your hair into a project, then give it to someone to strengthen your relationship with them. I guess this means everyone I’ve given things too now has a great relationship with my cats.)
My late uncle still had a sweater an ex-girlfriend had knit for him. Even though by that point he was married with two adult daughters. One of whom had claimed the sweater. So, um, it was really good knitting, I guess, even if the relationship hadn’t lasted.