When sex is not a high priority and the idea of doing anything but the act is more interesting. This is a multi-use phrase. Having children definately brings on knit a sweater. Dating a prude or someone with no vision absolutely qualifies under knit a sweater. When men use this term it is crucial to understand that someone needs to put them out of their misery immediately. All fabulous people.. honey, knit away.
I think my best friend is going through the knit a sweater phase, because she was mad at me wanting to look sexy for my new boyfriend. The sweatsuit and frizzy hair were also tell-tale signs that I should have shut up talking, but I didn't, and she bit my head off.