rebound relationships

I have a question, my brother broke up with his GF that he was seeing for a year. Within 2 weeks he already had a new GF, now he is all into her the sameway he was with his ex. How can a man go from one serious committed relationship into another committed relationship? Is this a rebound thing? Will it last? I really liked his ex GF, she is broken hearted and wonders how he could move on so quickly.

http://www.psychologytoday.com/blog/...-relationships

While it may seem to you that he broke up with her only two weeks ago, he may have broken up with her emotionally six months ago or longer and stayed with her physically for any number of reasons. i.e. fear of being alone, sex, etc.

I don't know if it will last; my stepson has had similar situations; we were looking forward to his marrying the last girlfriend and they seemed to suddenly break up and she moved away to another state and he took a new job! He has had his current girlfriend for 3-4 years now and before the last girlfriend there was another of that length, etc.

I don't think it is rebound. I think some people have an easier time when a relationship is over than others; kind of like when you changed jobs or move? If you are moving forward I think it is different from if you are "left".