3 weeks postpartum, feeling lonely.

I’m currently 3 weeks postpartum, almost 4 on Tuesday and this past week ive been feeling very lonely. I don’t understand why because my husband has been on paternity leave since our son was born, so I’m not really alone. He goes back to work in a week and the last couple of days I have been thinking about what I’m gonna do when he does go back to work, and how I’ll feel even more lonely. We have 2 dogs and we have our son, so I won’t really be alone just mentally I feel lonely sometimes. Is this normal at 3-4 weeks postpartum?? Tips or suggestions to help?