Most Helpful Guy
What you're asking has to do with an emotional condition/state of being. You don't understand it because you're a girl, not a guy. Girls place a fair amount of importance to their emotional state concerning situations. Guys... not any where near as much. To us, emotions are fleeting and temporary. We have them, certainly, but after a generally short time they're not there.
I love my wife, but I definitely do NOT feel that gushy, "I gotta be with her" feeling all the time.
When your boyfriend talked to his friends, he got advise and they left it to him to decide what he would do. "Most" guys will follow a logical path of thought, with priorities, and other factors considered. Emotional feelings (in those decisions) usually have a low priority to most guys.
As much as it pains you, guys usually do not give emotional feelings much precedence in nearly all of our decisions. I'm sorry this happened to you.