@lvenger: I'll agree its cliche but does make a bit of sense. Morlun referred to her as the "spider-bride" which is probably to do with their connection to the Other. As the Other always needs an avatar it would make sense for it to create the perfect "mate" for the avatar to pass on its genes and reproduce gauranteing a centre to the web every generation. I know Kaine is currently the avatar but he was not the Other's first choice it had to settle for Kaine when Peter rejected it. It also draws a parallel in real life spiders like wolf spiders and some tarantulas who take ages to find a mate but then pair for life when they do.
This whole spider-sense attraction thing is probably the Other's way of saying "You guys were literally made for each now kiss god damn it!"