Live-in girlfriend sleepover to friends?

My girlfriend of 2 years wanted to see friends of hers today instead of spending the bank holiday together.

I asked her to not spend the night elsewhere and come back home. I feel that this is not something in line with my core values.

I am thinking of breaking up with her since I made it clear that this behaviour would lead to breakup, yet she ignored me.

Am I extreme to expect my girlfriend to want to spend time together and come back home. for the night?

Live-in girlfriend sleepover to friends?
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