Fuck off, fuck off, just fucking fuck off! Learn to leave people alone when you know nothing about them. Do not take away something from someone when they deserve to have it. You know nothing about these two people, they share something that you can not understand. She might be is friend, but it does not mean that he isn't honest or gives a shit about his girlfriend. People have friends, but I guess that you wouldn't understand this because you have never had any from the start. You are too blind to see that he would never do something like that because you know nothing about him. You are too blind to see that she would never hurt him, because you know nothing about her. Does it bother you that they have an honest relationship, something that you have never had. They earned this, this is there time - not yours. So tell me why are you intruding, why are you being a fruit fly in a house with clean tables and fresh fruit. If they had problems, they would tell each other. If they were cheaters, they wouldn't be together. Not all people function the same way you do, learn to grow up because everyone else has, you're the only one left, you little shit.
Protip: if they wanted your opinion, they would ask you. If there was something wrong, they'd be upset. But the only thing wrong with this picture is you.