no two men are not married no matter what they claim, or what the civil law in your area states. No government has the right to declare marriage to be other than what God instituted, the union of one man and one woman. Since they cannot by definition carry out the fundamental act of marriage, they cannot be married.
You however have no personal knowledge of any sin they are committing unless they act out improperly in your presence. So you approach them as you do everyone who presents themselves to others as living other than an acceptable lifestyle, in Christian charity. You hate the sin and love the sinner, but you don’t make judgment about the state of their soul and don’t presume to know what there sins are. Yes it may be that you are not able to socialize with them, if their public activities are an occasion of sin for you, or if you would be required to approve of sinful behavior by so doing. That does not mean you have to be angry with anyone. There is no place for such anger in Christian charity.