Can I go to jail if his mom calls the police just for me staying a few nights at their house?

My boyfriend and I are both 18 and he still lives in his mother’s apartment, but she has been in a nursing home for nearly two years.
I decided to stay a few nights over (in a row) and now his mom says if I stay the night over there again, she will call the police. What could happen and can she do that?
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