Love is patient, Love is kind. It does not envy, it does not boast, it is not self-seeking, it is not easily angered, it keeps no record of wrongs. Love does not delight in evil but rejoices with the truth. It always protects, always trusts, always hopes, always perseveres. Love never fails. But where there are prophecies, they will cease; where there are tounges, they will be stilled; where there is knowledge, it will pass away. (1 Corinthians 13:4-8)
if he truly loves the girl and knows that she's already in a relationship, he'll just be happy for both of them and will not get in there way. a true friend will also be happy if his friend is happy.. that is IF he's 'GENUINE.'