My parents divorced when I was 5yo. My mom began dating right after her divorce came through, which occurred about one year after she separated from my dad. My mom began dating a man named Alex, who was a very nice man. She fell in love with him, and wanted to devote a lot of her attention to him. This made me very deeply jealous of Alex, but I really liked him also, because he was so nice to me and my mom. As a young boy, I know that I loved feeling jealous of Alex, and I loved having very deep feelings for him. But I also knew that Alex had a very different relationship with my mom than I did. He got to hold her and kiss her in ways that I could not, and he shared a bed with her. My mom would tell me not to come into her bedroom when she and Alex were in there together, because they were "spending special time together". All in all I was very jealous of Alex, but I was very happy for my mom, because I knew that Alex made her very happy, even though at my age I did not know all the reasons why. But your sons is 21 years old. Why is he not happy for you?
