It is amazing @OneDayIHopeItsGoingToBeMe It's the best life being loved and cared for by your partner/husband or wife... And loving them back...
I have been with my DH over 35 years and married for over 30 years..... 2 adult children - left home now...
It's lovely to have someone to chat to, someone to share a bottle of wine with in the evening while you watch a film, someone to share life's burdens and woes with, someone to play games and sports with, someone to go on walks by the river and in the woodlands with, someone to share life's successes with, someone to raise a family with, someone to socialise with, someone to share financial burdens with, someone to fight in your corner, someone to care for you when you're ill, someone to go on holidays and day trips with, someone to laugh with, someone to cry with, someone to go out to dinner with or just share a maccie d's with, someone to grow old with, someone to love, and someone to love you back.
We do have our own individual friends and individual hobbies, and do some stuff away from each other. It's healthy to spend some time apart, and makes you appreciate the time together - when you come back together at home. 
I'm just really sorry you have never had this, and you crave it so much. And I'm sorry for a few others on this thread who have clearly never experienced being in love either. It's amazing.
Being married is wonderful, being in a couple is brilliant, and being in love is the best. I would not switch places with a person who is single for all the tea in China.
As a few posters have said, it's the warmth and security, having someone to share life's trials and tribulations with, and knowing you have someone to fight in your corner that are some of best things.... Like others we have had our ups and downs - more ups I have to say -
and on the whole it's been a wonderful life with him.
I hope you find your special person one day, soon. 