Thank you for your letter - and I hope many people will take it to heart. Some day, they too may be facing an empty house as they grow older, and now is the time for them to begin practicing Jesus' words in the Golden Rule: "In everything, do to others what you would have them do to you" (Matthew 7:12).
It's easy when we're young to get wrapped up in our own lives and lose sight of what's happening in the lives of others - including our parents. But life can be lonely as we grow older, and I'm grateful for the way our own children (and their children) have kept in touch over the years. This means even more to me now that my wife, Ruth, is in heaven. But I know this isn't true in many families, and my heart goes out to them. Even when He was on the cross, Jesus reached out to His mother, Mary (see John 19:26).
Let me suggest two things you might do to bridge the gap with your children and their families. First, reach out to them - call them, send cards on special occasions, write e-mails if you can, and so forth. Don't complain or become a nuisance in their eyes - but let them know you love them and are interested in them.
Second, reach out to people around you who may be even lonelier than you are - widows, singles, older people, etc. Your church would be a good place to start. God will use you to encourage them - and they in turn will encourage you.