Dreaming of one's husband being involved with another person

I am a happily married woman with two kids Alhumdulillah. Me and my husband got arranged married and we both are happy. We both trust each other and I have no doubt he is doing anything he should not. I have strange dreams about my husband. In starting, I did not care but now I am very depressed. I see in my dreams that he is married to someone else. Sometimes I dream that he is involved with somebody else and this lady is sending him love letters. Once I have dreamed that he is sleeping with his second wife. I am so much worried. Why do I see these kinds of dreams? I am thinking of it throughout the day and can't forget what I have seen in dreams. I also asked my husband, he said to me that I am crazy. I am the only one in his life and I should not think about it because dreams are not true. Please guide me what do these dreams mean and how I can get rid of them. I see these kinds of dreams very often 6-7 times a month.