Why does your wife show more love to a stranger?

If your talking about the man she is seeing, yes it is a bit different. If I don't know better the man she is seeing is giving her more time and attention, that you probably haven't done in a long time. Could it be that after a few years of being married to her, you become more comfortable that you forgot that your wife has also some needs like you. Sometimes husband do forget about us wives. Maybe your wife missed hearing you telling her how much you love her and appreciated everything she has done for you.
I know what I'm talking to you about because it's happening to me, to my marriage. I think the man your wife is seeing, is listening to her, it supposed to be your job. The man I married also said to his his ex mistress and me that I never listen to him talk. I wish that is true because I thought the man I married is a quite type person who rather listen than talk. But I was wrong, he loves to talk, it just not with me from the start of our marriage.
So if I were you, I will talk to her, really talk to her and ask her where the two of you stand now. Ask her what you done that made her look at another man. The ball is in your court now and this is up to you to fix it..