While I agree that an advisor dating a collegiate's ex in the same sorority is not cool in my eyes, I don't think it is any of the sorority's business to worry about sisters and their personal relationship. If having this person as an advisor to your chapter is detrimental to the chapter's well-being, I would contact your HQs and ask for a new advisor. But this doesn't sound to me as grounds for anyone's deactivation.
33girl, I agree wholeheartedly with you!! 5 years out is a good start
