John T. Cacioppo said this quote

Real relief from loneliness requires the cooperation of at least one other person, and yet the more chronic our loneliness becomes, the less equipped we may be to entice such cooperation.

~ John T. Cacioppo

There are extremes within any population, but on average, at least among young adults, those who feel lonely actually spend no more time alone than do those who feel more connected. They are no more or less physically attractive than average, and they do not differ, on average, from the non-lonely in terms of height, weight, age, education, or intelligence. Most important, when we look at the broad continuum (rather than just the extremes) of people who feel lonely, we find that they have the capacity to be just as socially adept as anyone else. Feeling lonely does not mean that we have deficient social skills.

~ John T. Cacioppo