And fans know that Abraham went through some terrible times before he tagged along with Eugene (under the belief that Eugene was in contact with the government).
While Abraham and his family survived for a short amount of time after the shit hit the fan, his wife was raped by one of the other survivors they were holed up with, and Abraham rage-killed that rapist and others, which scared off his wife and children.
He later found their walker-chomped bodies, which is what led to his suicide attempt.
Houston is important, of course, because that was established as the pre-apocalypse hometown for Abraham, and he assumedly lived there for the bulk of his life that wasn’t devoted to whatever military tours he went on.