How to react to her periods mood swings?

Her period cramps and mood swings are heavy.
We're neighbours and in relationship. Today we went a day trip with both families which we planned last week.
But today her periods started and she was so moody and was suffering from extreme pain.

She told me I'm the one who planned trip, I'm the worst, getlost from my life.. kinda.. I understood it's because of her frustration and tried a loooot to comfort her. She was ignoring me the whole day. I really got upset.

Just before end of trip, she said "it was mood swing, i love you.. I cried a lot for nothing"

I ignored her 😑 her mood changed again !

How to react to heavy mood swings and such hurting behaviour?
How to react to her periods mood swings?
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