Dear IndianGirl you are being honest. Facebook has a lot of good uses but the posts are an unrealistic view of another person's life. People post nice vacation pics. They don't post about how everyone was irritable with the waits in the airport, the tight seats and having to pay for airline food. You don't hear the kids whining that they didn't want to come on this dumb trip and wanted to stay home with friends. You don't hear about the lost luggage, bad packing choices and the credit card bills. What you get is a few chosen pics for seeing everything at its best.
People post edited photos of themselves. No woman in her right mind posts side shots or ones taken from below (it makes normal people look like Jabba the Hut).
The jobs, homes, trips and family posts are only the good stuff. The occasional person might ask for prayer for a rough time. Maybe you have that friend that always posts doom and gloom (emotional vampires), but trust me, you are not seeing the full picture. A good part of their lives would make you give thanks for not being them.
As for lonely when you are elderly, I think a lot of us wonder about that. I am 55 and yes I get scared. My response is to create and gather a community of women around me. Look for women with positive attitudes, can do and make do types of people. Look for people who enjoy life, whose love for God is made real in how they handle life and how they treat other people. It will give you hope for the future. Being alone goes beyond, "Will I find a mate?". I realized I didn't have to be alone if I had good friends who were willing to be there for each other, help each other is practical ways. That is worth gold. I wish you every happiness. Your posts show you are intelligent and interesting. I bet it would be fun to go out for coffee with you. I pray that 2020 gives you joy and hope.