He'd been a very friendly, outgoing person; laidback, easy to talk to, great friend and a great sense of humor. But that was before his wife and daughter were brutally murdered.
The grief and anger had been expected by all his friends and colleagues. He eventually overcame it, but he no longer was the same laidback, outgoing person. He still talked to his friends and colleagues, but the humor and easiness was gone.
Nobody really blamed him. He may have passed the grief, it would take a lot more time to put things behind him and really move on. But he didn't. As time passed, he became colder.
The change had been so slow that initially his friends and colleagues didn't even notice it. But as he slowly became distant and even quieter, they realized he was falling apart.
At one point he briefly brightened up a bit, but shortly afterwards he reverted back to his cold ways. One colleague figured out the cause of his brief improvement: the death of the scientist-slash-astronaut who tried a new kind of space propulsion. Apparently, the murderer of his wife and daughter was in some way related to this man's family.
After some time, he changed career. 'Presidential Adviser' or something like that. Probably for the best, because at that point he had completely stopped communicating with his friends, and only talked to his colleagues when it was work related. Lady Liberty would be a better conversation partner. In his new job, he'd barely have to see or talk to anyone.