My opinion is that there relationship is just as co-workers.. (i hope so coz i could never imagine gin and sherry having an intimate relationship... I can't accept that! NEVER!! )
Back to the topic:
Maybe Gin hates Sherry so much because she betrayed the organization. I mean, he hates traitors, right?
Another is that, He desires Sherry but Sherry just plainly HATES him...(wow, that felt good)
Well, that's all