When Buddha ran away he was ignorant. He was seeking, he was depressed and upset. Without knowing the reality of life he felt life is meaningless.
In that state of low energy, depression, he went on seeking.
Once he found, he returned back. He took great responsibility not just of his family, but for the entire world, the whole society. When Siddhartha became Buddha he came back to the society and for 40 years he traveled around and did great work.