There is something you can do. You can use your voice to set him straight.
His return will be an excellent time to tell him that you are not interested in him, other than as a co-worker. Just matter-of-factly, "I want to set something straight - I am only interested in being your co-worker and nothing more." If he doesn't want to believe it, you will have to repeat it. If he tries to debate it, you can repeat it and tell him that there is nothing more to discuss, then end the conversation. Be sure to act accordingly after that; keep your distance from him and treat him as a co-worker and not as a friend.

Your boss doesn't get to decide who takes you home when your ride doesn't come. Keep enough money for a cab or bus with you at all times and you will have that taken care of for yourself.

If you feel that you can trust your boss, you could confide in him. "About "X", I'm not interested in him as a boyfriend and I'm going to be telling him when he comes back."

If he continues to harass you, you can talk to your boss again, or report him to your store's Human Resources department.