He made his friend decieve his girlfriend and ofcourse, deceived his girlfriend. He is not justified using respect as a value. Max's actions had the potential to destroy all three relationships and it almost did. He did however, manage to bring Jay and Sam togethor therefore he is justified by principle of utility. Do what one wants as long as it does not harm others.
Harm means emotional and physical.
Max upset Jay by asking him to try to sleep with his girlfriend. Max upset Sam by deceiving her and, she stopped talking to him. He therefore, is not justified using Liberty as a value.