Pain shopping = seeking out needless pain. Some pain is useful to us, in that it helps us get to the truth we need to hear, or clarifies our thinking, or helps us make hard decisions. Other pain just hurts us for no reason. It's masochistic, and takes us backward rather than forward.
Pain shopping is asking for details that will hurt you rather than help you heal, like what their favorite sex position was or which bra she wore when they were together. It doesn't help you understand the A or your WS any better. It only adds to the mess in your head rather than helping to clear it out.
It might mean re-reading email and texts that you know will wreck you again. Or continuing to gather info even after you know for sure your WS is being unfaithful. Or continuing contact with an AP who is only out to hurt you. Or demanding apologies from an unremorseful WS. Pain shopping is banging your head on the wall, and none of us should do it.
[This message edited by krsplat at 6:51 AM, July 30th (Wednesday)]