Is it normal for my stepdaughter to cry every night?

My stepdaughter just turned 8. She spends half the week with my husband and I, half with her mom and her new husband. We’ve been married for almost 2 years, and for the past….6? 8 months? I don’t even know how long anymore, but when she’s at our house, at bedtime she starts crying because she misses her mom. At her mom’s house, she starts crying because she misses her dad. Every night. She can call and talk to either parent, and usually does, but it just seems like it’s not getting any better, and I’m worried about her adjusting. Is this normal or healthy? I just feel really bad for her and wish she wouldn’t suffer so much.