It is difficult to speculate what "K" issues are without a bigger picture of the situation. Has K had issues with other male partners you've had in the past? If so, are the current issues connected to the fact that D is now a member of your household.
It just an opinion, but I suspect the most men are protective by nature, its possible while K is not jealous of the relationship you have with D, some of the male protective instincts are cropping up.
These may resolve themselves over time as "K" relationship with "D" matures, D can do little to address the issue with K. K will need to resolve the issues within himself.
I think your communications with K will be helpful too. Re-exam your last series of interactions with K. Have you unknowingly, cast yourself in more of a sibling role with K than you realized?
Or has K inadvertently cast you into the sibling role?
Either way, the only way to break "k" mindset is to present yourself as more lover than friend to K, IMHO.
Last edited by 47newbie; 10-24-2011 at 06:04 PM.