How do I deal with my stepson’s girlfriend?

They’re dating since 6 months and they seem happy together. She is very nice when my stepson is around but when she sit with me alone it’s completely different. She tells me to stop treating him like a child and to stay away so he can quit talking about me being super mom. She usually gives me weird looks for no reason and whenever I help him with something she gets angry and wants to leave. I am not forcing myself into their relationship but when he ask for help me & his dad and his little brother are always there as family.

Both of them are 18 years old.

How do I deal with my stepson’s girlfriend?
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