Most Helpful Girl
It depends on the girl's personality. It also depends on the relationships she had with here ex. Girls are very emotional after a break up, some might talk to a guy friend who would support her and be there for her after a break up, she didn't latch on to him, she just seeked support and might develop genuine feelings for him. Some other girls would use someone to forget about their ex, they replaced that void as soon as they broke up. I think it all comes down to personality.
Most Helpful Guy
It could be either or both honestly. Most people feel that strong rush of emotion after a breakup because of the pleasure they felt when they were in a relationship and they want it back.