Can you hear me now? 50 and lonely

What is it about women in their early 50's that they always seem lonely?

In observing the women I live with, as well as relatives and friend's mothers, they all seem desperately lonely. My not very social aunt, in her mid-50's, has been making a lot of attempts to reconnect with friends from her youth, emailing people who might have went to middle school with her, calling people who were my grandmother's neighbors in the mid-70's.

My mother, whose best friend passed away several years ago, has also reconnected with college friends who she hasn't been in contact with for years. My mother's quite social and has lots of friends. But on any Friday night, I could walk into the house to find my mother sitting alone and looking relieved that there's someone finally someone to talk to.

Even a friend's extremely independent mother, a socialite who throws unparalleled parties and has what seems like an exciting social life, who has become a drain on her children because she refuses to be left alone.

How unfair is life to these women?
Most of which have dedicated the past 15 years, at least, of their lives to their families. Spending their time between making sure their children are healthy, happy, and somewhat successful. Feeding them, helping with homework, keeping them entertained, all the while not realizing that their own relationships are unraveling before their eyes.

Then waking up one morning, after these kids have grown up and are leading their own lives, to a seemingly empty life?

What happens then?

Do they frantically try to collect the pieces of a life that once was?
Is that what happens?
Do they cling to their children and meddle in their lives?

Most of my friends, married or married with children, have already began pulling back from a lot of their friendships, mostly because of social obligations and limited amount of time, which is understandable. But I wonder, whether this is where we, as women, set ourselves up for the inevitable loneliness in middle-age.

We never learn to maintain friendships. Our chosen relationships are not a priority.

What about men?
Does the same thing happen? Or is our culture more forgiving of allowing men to have friendships throughout the years?

Are we all, regardless of age or gender, lonely and just keeping busy?