The "bristle reaction" is an involuntary physical and emotional recoil from a partner's touch, often in long-term relationships, stemming from feeling pressured for sex or overwhelmed by daily demands, causing the person to tense up or pull away, leading to confusion and hurt for the initiator and further distance. It's commonly linked to mismatched libido, an association of touch with a demand, feeling emotionally disconnected (like from "choreplay" or uneven workloads), sensory overload, or underlying issues like trauma, and can be addressed through open communication, redefining non-sexual touch, and understanding the root cause.