I thought getting married and settling down are the same things
Most Helpful Guy
I would take that to mean that he still wants to lead an dynamic life. I'd image he wants to get married but doesn't want to do the whole "start a family, buy a house and live there for the next ten years and work a Monday-Friday desk job". I'd say he wants to explore the world, try different things in life, work/recreation - not just stay in one place.1
Most Helpful Girl
I think those are the words of someone who is afraid of losing their freedom/identity inside their perception of what "married" would be. Ask them, ask what it would mean to "settle down." I'm betting your answer is in their response to that.
Having freedom and identity inside a marriage doesn't have to be compromised, and it's much better not to. I'd really just ask what they have left in life they want to do, what they value in their time not married. That's what they're afraid of losing, but want a partner in that (hence the married part). That's honestly the ideal relationship... honor your differences, freedom, and identities while being committed partners through the adventure. Push each other to grow, both in the partnership, but as individuals too. Want them to be the best them, even if some of it is outside of you. That's why it's a partnership, not any of those silly, sappy phrases of "completing each other," or "becoming one in everything." Nope. Partners. Whole people, committed to traveling time/life together.2