Most Helpful Guy
Well, he's a jerk, and your friend should go out and find a nice guy. Honestly, when people do that, they usually don't come back, and even if they do, they usually have some half-ass excuse that you know isn't true. This guy is just extremely inconsiderate.
Most Helpful Girl
Being ignored is the worst feeling, it almost makes you feel like you did something wrong in order for this person to be ignoring you. Your friend hasn't done anything wrong at all, all she has done is care for this person and they are obviously being very unfair and not taking that she cares into consideration. When we care about someone we usually let our mind run away with us, thinking that we can solve what has made them suddenly turn. He may have reasons for stopping calling her, he may be busy with things going on in his life or he may have something serious happen with his family life. If your friend had this guy on social media, she might want to send him a quick message voicing her concern as she hasn't heard from him in a while, if she hasn't already done that. If she has done that, then I would advice she lets him come to her. Men do that, they hide away from intense situations and think that if they push it away, it will go away. The truth is, these things don't go away, so he might as well be honest with her and tell her what he wants in all of this, instead of making the poor girl wait around. Tell her to do things that she loves doing, hanging out with her friend and showing him that she is just as fine without him, show him how happy she might be (even if she doesn't feel it right now). If it is meant to be, he will soon come running back and realise what he is missing.
Hope this helps a little, Good Luck to your friend and tell her to Keep Smiling!