How do you guard your heart?

If falling in love, or having a romantic relationship is not a good idea for you at a given time(for example you will be leaving the area soon), but you are very lonely and single, how do you prevent yourself from falling for someone while continuing to hang out and be friends?

My personal example; I am going on a long term road trip very soon, and met someone I like very much. We’re both interested in similar endeavors. We are coincidentally reading the same book right now. But he just moved to the county, while I am getting ready to leave. I feel a very strong connection to him (not to mention he is gorgeous. ) We are both lonely, and possibly interested in a relationship, but not in short term flings.