I can imagine your sadness and worry for your children. All you want to see at this age is happy children and grandchildren.  You can still be a family and have your kids come over and do stuff. Once a month, is not too much to ask – maybe they need that bonding time too, since they are alone. Find creative ideas to get together as a family and  do some fun stuff, so it does not sound so melodramatic.

I am pretty sure that your kids will eventually find their soul mates and settle down.