I don't think the daughter's name is on the deed to the property, so the only people deciding when, where, and with whom sex is occurring on the property would be the mother and father. I get the impression the boyfriend and father have butted heads before. Something along the lines of, "if I catch you with my daughter alone in her room again, I swear I'll kill you."
But...if the boy was running away and was unarmed, the father is in a load of trouble.