Eh, men are the gatekeepers of relationships, so we can end it however we see fit. Just like women can have sex with whoever
they see fit. Balance
Anyone can do whatever they want, but that doesn't mean that there isn't any duty nor responsibility behind it...
It would be one thing if the guy just met the woman and suddenly decided that he didn't wanna deal with her anymore and it is another thing to be in a relationship with someone for a while and abruptly end it without any explanation.
What harm would it be for dude to have the conversation with his girlfriend about some information he heard about her from someone else? Who is to say that the 3rd party individual didn't have an alterior motives??
At this point, we are all speculating on what went down in their relationship, however I maintain the position that there are rules to this iish when dealing with someone on a romantic level...
Lastly, Idk how you deal with women, but I believe in being fairly transparent with someone. But, I also believe in being allowed to keep certain information private.
Dude should have had the conversation, heard was was told to him and if what he heard wasn't satisfactory for him to stay in the relationship, then move on. At least at that point, closure was given and his conscious was cleared...