He is shown to be completely clueless and unaware of others' feelings, not understanding the meaning of friendship. He often states things factually, not understanding how what he says can upset people. He decides to assist Elizabeth on her journey, not because of a desire for justice, but because he felt obligated as a member of the Seven Deadly Sins. Since Gowther doesn't understand emotions, he goes to great length to understand them. For example, observing Meliodas and Ban's friendship.
(Source: Nanatsu no Taizai Wiki)