It's wrong to deceive your partner.
Dave wins money at the casino and comes home with a wad of cash which his wife Jane sees and asks him where he got it.
Dave wants to respond to Jane's question.
Dave tells Jane he was gambling, and he won it at the casino.
Dave tells Jane that he recently got a bonus from work but that for some reason they had to pay him in cash.
Jane is not happy Dave was gambling but is happy he is telling her the truth.
Jane is suspicious of Dave's explanation and doesn't trust him as much.