well tricky one indeed!! I have had issues like this myself BUT.. mine were with my brothers girlfriends.. yep you heard me right .. my BROTHERS!!
My younger brother and I were always close..could laugh and joke around, hang out together and talk for hours

.. anyhoo he went out with this girl years ago who hated how close we were!! Towards the end of their relationship he was expected not to talk to me.. not to enjoy himself around me or joke around with me. It changed our relationship for awhile there... I would try to talk to this silly girl lots of times.. tried hard to explain..

HE IS MY BROTHER!! I'm NOT a threat to your relationship

Her response.. I hate how you are so close.. its not right..

errr yeah ok.. sure

anyway, thank god that relationship ended and he is now with the most wonderful woman he could possibly have who is like a sister to me
but.. my story doesn't end there

my older brother, who I also get on well with,, married this woman who ALSO did not like how close we were.. he would come to visit with my niece and nephew so they could spend time with my kids .. and his (now ex wife thank god) would ring me up and abuse me and leave crazy msgs on my answering machine saying things like.. he loves you more then me.. you are a bad influence on him etc etc .. AGAIN,, I tried to talk to her and say HE IS MY BROTHER!! of course he loves me BUT he loves me differently to you .. again it fell on deaf ears

what do you do? some people are not going to accept your relationship with friends or family no matter how hard you try to be nice to them and befriend them .. others are awesome and welcome you with open arms