OK, so you are saying that in the situation where there is a conflict of interest then HR should be involved so that the matter can be dealt with fairly. In that case why not bring the matter to HR when there is an issue to be resolved. This is a situation of a higher level employee abusing their power over a lower level employee and could happen whether a romantic relationship exists or not. What does HR having foreknowledge do to help prevent such a situation?
For one, it leaves a paper trail. Assuming that HR says "OK, thanks for telling us"...now you have a third party that can nominally monitor the situation. Right now, it's just Keith's word (he claims to not have any impact on his partner's fate at the company, but how can we ascertain that he's not being misleading?) against his accuser's.
