As we grow older, our circle of friends becomes smaller. This is natural. For most people, their largest number of friends will be at school/college/military due the nature of the environment. Once you leave, your friends will be your co-workers, housemates, neighbours. As you grow older, many of them will die off. Eventually, you will be left alone, save for your spouse and children. Such is life.
It's only available to players that joined pre-2000's. You just go to your profile under rewards and you should see the marital lootbox. You should also recieve a "#1 Parent" cosmetic.