I think the people who are miserable single might be the same ones who'd complain about their marriages. In either state you can focus on the good or bad parts. It is a choice.
There is a big difference between life and sentient life. There may indeed be life on Pluto or planets in our solar system, and they may be different forms such as fungus. It would be alien life but have no relation to the aliens of 1950s sci fi and a disappointment to those looking for UFOs...