It happens my daughter was 6 when I had my son so she thought the same way. So I set up special days once a week where mommy and her did something even if it was just a movie we do it still every now and then usually it's going out to play Pokemon Go but with the cold weather we have held off and had a movie night instead. So talk with him and maybe set up special times to do something with him that you both enjoy doing.

Mommy and me time! My oldest did this too. Also try to make him excited about the baby coming by putting him in charge of certain things. Some kids like that bc they like feeling like they’re the big brother or sister that’s in charge.

With my daughter it was a phase until i had my son... she helped feed him, bring his diapers,clothes when i needed them so that wAy she felt like she was helping as well ... while i was prego i did try to give her all the attention she needed and ease her into having baby brother. It will probobly last a while. Just re asure him that you do love him and it wont chhange he will jst be a big bro and he can help out when needed. Its normal for them to react like that mama, it will b okay. There was a time my daughter wouldnt want nun to do w me when i was prego but slowly she got used to it n like i said , she said she will help mama with lik bro and then when i did give birth she wasnt jealous at all she tried to help all the time n still does. If u need to talk more message me

My son was so against the baby when I was pregnant. I thought he would resent the newborn but he totally switched. A lot of people reassured him that he was going to be a great big brother, and everything that happens with the baby happened to him when he was a baby. My son walked into the hospital room and started crying but I instantly started joking around because the baby was farting and my son started laughing. And he’s been good ever since.

Just have a talk with him and tell him you will always love him more then anything no matter what and spend some extra time with him.