When we define an act as "holy of holies" what comes to mind? Maybe: Dying Al Kiddush Hashem, learning 20 hours a day, davening with intense kavana etc. etc.
The gemara [Yoma 54a] teaches us something that is so remarkable that it is nothing less than a REVOLUTION in our conception.
When the Jews would go up to the Beis Hamikdash for the 3 regalim, the curtain that covered the holy of holies would be removed so that the Jews could see what was happening there. This was obviously intended to be a lesson for their daily lives. It wasn't just to satisfy their curiosity or to חס ושלום take pictures and post on their Facebook pages.
So what was going on in there [the suspense is killing me!]?
The Jews saw the Keruvim hugging each other and were told that this symbolizes the love that Hashem has for His people!
Let us see Rashi's comment [ד"ה הכרובים]:
"מדובקין זה בזה ואחוזין ומחבקין זה את זה כזכר החובק את הנקבה"
"[The Keruvim were] clinging to each other, holding on and hugging each other like a male hugging a female".
Meaning, to hug one's wife is an act that is קדש קדשים - Holy of Holies. Is that SOMETHING. You want to be holy? You don't have to fast 40 days or dunk in ice cold mikvas. All you have to do is give your wife a hug. Hashem was showing us that he loves us in the holy of holies with the image of a man hugging his wife. He used this image in order that we apply this to our lives.
You follow this Rashi and you restore shalom to your home..... THAT is the holiest.