When I come inside, I shut the door. I don’t hang around in the doorway, keeping it open–just in case I feel the need to leave again. If I really need to leave, I’m perfectly capable of opening the door to go out.
In my opinion, a relationship operates the same way. If you want a relationship to work, don’t act like you’re ready to flee the scene at the slightest provocation. Don’t worry about “keeping your options open” or avoid doing relationshippy things “in case it doesn’t work out.” That just shows you’re not comfortable and you’re not willing to do what it takes to make things the best they can be.
If you want to have a relationship–a real relationship–don’t worry so much about your getaway. Come in. Sit down. Kick off your shoes and stretch out a little. Make yourself at home. That’s the only way to find out if it’s comfortable or not.
Get to know your possibly-significant other. Meet the people in his or her life—and meet them halfway, at least. Make an effort to get to know them, and give them the opportunity to get to know you. Don’t judge people if you haven’t made the time or effort to find out who they really are. Make yourself available; don’t hide in the corner, and then complain about how misunderstood you are.
If you are in, come in. If you are out, get out. Commit to trying or commit to bailing. But in either case, shut the door behind you.