Companionable. It's the most direct translation, and it's very close to how we use the word "gezellig". We just use the word a lot more frequently. The warm feeling you get when you are with friendly company, even if that's just your own company, that's what we call companionable and it's a theme that's central to Dutch culture. If you'll agree Christmas is the most companionable time of the year, I think you're very close to understanding to why the Dutch want everything to be companionable.