Match the question to how well you know him
Start with an experience he has already mentioned. A story about changing jobs can lead to a question about what makes work worthwhile. You do not need to jump from small talk to his most painful memory to have a worthwhile conversation.
Do not read an answer as a commitment
Someone can talk openly and still want friendship. If you want to know whether the interest is romantic, ask that directly at an appropriate moment. Keep these questions for learning about his life, not decoding clues. Share at a pace you are comfortable with, and leave room for him to pass.