Ask about a real decision
Start with something your boyfriend is choosing now: a job, a friendship, where to live or how to spend his weekends. Ask what matters to him in that choice before asking where your relationship fits. His answer may reveal a priority you would never learn from asking for his biggest dream.
Leave room for separate lives
A useful conversation includes what each of you wants to keep doing independently. If a plan affects you both, describe the practical effect rather than testing how much he cares. You can disagree about moving cities and still understand each other better. End by naming the question that needs another conversation, not by demanding a promise tonight.