Travel....or pick up a new hobby....or start a graduate program....
The reality is a good majority of people get married. However, the reality is also a higher age for marriage. (seriously the number of my friends who are engaged/seriously dating/recently married has increased TONS as we hit late 20s....)
So, what to do in the meantime? ANYTHING. Literally anything.
It's easy as a single to do one of two things...(1) overcommit. Everyone claims you have "free" time and should help with this party, church event, volunteer opportunity, etc or (2) not get involved, stay home, "WAIT" for a spouse and family.
Pick an option in the middle...save some time to do what you want to do. It's not selfish (despite many articles written about how singles these days are always selfish and enjoying their "ME" life) Choosing to pursue travel, hobbies, and even missions while single is wise with your time. Being married has advantages that should be enjoyed. BUT Being single does too. One of the single "pluses" is having a little more freedom!
While single, I sold my ring to pay for backpacking trip to europe, got a law degree, went on a second European trip to eastern europe, lived in DC 2 summers in Massachusetts 1 summer, went to Africa, ran a half marathon, etc.
So, what country do you want to visit? What hobby do you want to start? Go ahead a do it!!