Do you think my partner is spending to much time with her family?

my partner and I have been living with each other for 5 years. We spend most of our time home because we have children, ages 13 and 18, and we enjoy being home. But, every weekend she spends time with her mother and her sister and her sister's kids/grandchild. She asks me to come, and I use to, but it's no longer fun for me and I don't want to every weekend. So, I don't go but she does. We have nothing plan but I still get jealous that she wants to be with them every weekend, instead of being home with me.