I was married for many years to my first wife who died childless. Since her death 5 years ago I have been saying Kaddish daily. I remarried almost 3 years ago and now that we have “mirpeset minyanim” my new wife hears me saying Kaddish for her. I know it bothers her. Is one allowed to say Kaddish for their deceased wife if they remarry?
A man should not say kaddish for his first wife after he is remarried, because it causes ill will and bothers his new wife, as she will rightfully fell that your mind is still on your first wife. say kaddish for his first wife even though he has already remarried. This applies especially due to the fact that it is after the first year, (although even then it should not be said) What you can do is to hire someone else to say kaddish for her.
Be’er Moshe 4-104. Tzitz Eliezer 8-34, Yaskil Avdi 4-4, Nitei Gavriel Aveilus 49-11.