Daughter feels lonley

She’s (5 almost 6) ok right now and happy, but last night she was just soo sad and crying so hard at first was mad and taking it out on things when I persisted to ask her what’s going on? What’s wrong? She was hanging out with her dad for a bit but came back home walked in crying at first saying her dad got mad at her for no reason, which she still hasn’t told me but I’m sure she will eventually. She then starts crying again like bawling saying she just feels lonely when she’s not at school, she just started school this year and is an only child. Rarely sees cousins her age on my side and her dads side has no cousins her age. It made me cry too with her, and I just tried to calm her by saying it’s ok and she’s not going to be lonely forever since I’m pregnant and she will have her sister soon. I’m barely 5 1/2 months so still some time but I just tried to reassure her. I felt so bad and sad with her. It’s just us two who live together so I can understand her loneliness. Today we’re going out to the mall, gonna try and spoil her a bit so she can feel just a little better more.

What did you do with an only child?