I think this topic hits on one of those which can be innocent and come from a pure heart, but which could also be a symptom of an underlying problem or potential problem. We should all be reflecting with Jesus on our spiritual health from time to time. Satan will use anything to turn our lives against us.
Everyone seems to have equated singleness with romance, but I occasionally do miss the days of video games through the night (before wife and kids), or just hanging out with girls with no romantic strings attached. Being single had its perks. Yes, I think about it sometimes.
Marriage isn't necessarily the evolution of life from singleness either. It's not necessarily more responsible, blessed, righteous, or a better reflection of the life God has for us. Seriously, how many marry because they think, "if I get married, I can spend more time pleasing God." Quite the opposite, no?