When Grandpa Gohan saw him (Goku)for the first time as a naked baby in a spaceship ,little did he knew that he was actually send from outer space to destroy earth and its people. So, Gohan took him home,cared for him but he was a troubled child,a evil, still grandpa was good to him. when Goku got hit in his head severely, he was critical, battling for life. Gohan took care of him and eventually recovered from trauma and Goku lost all his previous memory. After recovery, Goku became a happy child and loved his grandpa Gohan dearly.
When Gohan died, Goku was devastated, neither knew how he died. He lived on his own, met many of his friends including Bulma, his best buddy Krillin, master Roshi,Yamcha and future wife Chichi. After his marriage, Goku and chichi had a baby boy and named him Gohan
As far as not being a good husband, During Cell games,cell was getting ready to explode to destroy earth. in order to save the world from evil cell,he decided to make cell blow himself in King kai’s planet and not on earth using his instant transmission power, eventually sacrificing his own life for the sake of others. Before doing that, he bid his son Gohan goodbye and his last words were”Please take care of your mother”
He thought about her before he died
As far as his intellect is concerned, I agree he was dumb in some instances, but in battlefield, he showed extreme cleverness, for eg: In planet namek, Captain Ginyu was using his powers to swipe his weak body with Vegeta’s and to use his strength later. Unknown to Vegeta, he suddenly became numb due to Ginyu’s power to swipe bodies. As Goku knew the trick, he saw a frog nearby his reach, grabbed hold of him and threw it in between both of then, resulting in Giynu getting trapped in a frog’s body and not in Vegeta’s, saving Vegeta.