Pety lies

I have been wondering why my husband lies about very pity issuies . He can lie about why he came home late and when i read his messages i realise he went out with his friends and he had said he stayed late at work. He says he sent his mum money but i later realise he sent his sister. I just dont understand why he should lie on things that dont even matter . I always tell him to tell me the truth because this are not the only incidences then when i have forgiven i realise he just lied to me again. Please help me understand because im really feeling confused. Funny part is that when i confront him with truth he denies until i produce evidence