I had a very religious Aunt (not a JW) who was extemely unhappy too. I used to listen to her go on and on about how I needed her religion, but all I could think about was how miserable and unhappy she was. She would reference the "future happiness" thought as well. Why would I want what SHE has? It looks like a miserable way to live. But to her, misery was happiness, and misery loves company.
A miserable existence was some type of martyrdom for God, and isn't He just SOOOO impressed?!
I only visited a KH once, but it was on the Memorial night. Of course, there was all that "love-bombing" going on, so I guess if you were looking for a place to be accepted, it might seem perfect. If you are looking for friendships, you might over-look the unhappiness of others, if there's a lot of attention lavished on you personally. Little do you know at that point that it is all an illusion. It is all conditional.
The most contagious Christian I have ever met was my father-in-law. He doesn't push "religion". He lives a pattern of Christ-like love. He makes you want what he has. Everyone should have at least one relative like him. He is amazing!