Will a homeowner be held responsible if invited guests of drinking age injure themselves while intoxicated without the homeowner present?More...

It is possible.  Homeowner liability cases are based on a few details:

1) Is the injured party an invitee, a licensee, or a trespasser.  In this situation, the victim is a social guest of the homeowner, and there is a licensee.  "The homeowner is usually liable only for willful or wanton injury to a licensee."

This would sound like the intoxicated individual is on their own. However, the second component to this case is:

2) Negligence.  When the victim broke his arm, was it because of some negligence of the homeowner?  A loose floorboard?  An exposed pipe of some kind?  If the court finds that the homeowner is negligent in some way, then she could be responsible. 

All of this would depend on the exact wording of the Maine statutes and on the other circumstances surrounding the breaking of the visitor's arm (how, where, etc.).