Was kinda expecting this as an actual ending, but seeing it actually drawn, really is soul crushingly depressing. Poor Homura, so many bad ends in doujins ;_;
What I see as the reason it keeps activating independently is the "to become someone who can protect Madoka" bit: If Homura is able to defeat Walpurgisnacht, she has fulfilled that intent. The maximum amount of time she'll ever be able to spend with Madoka is however long it takes to either protect her or fail to do so, and the power will kick back in every time the condition is nullified. With this in mind, could she even die? Would her magic intervene the momen before she dies, when she otherwise would cease becoming someone ("anyone", really) who could protect at all?
