Second, the PMS myth also contributes to the stereotype of women as irrational and overemotional.

第二，经前综合征的迷思对女性不理性和过度情绪化的刻板印象的 形成有所助益。

This is overreacting or being overemotional.

这是反应过度或情绪化。

Maybe you get sad, you cry for no reason, and you will become overemotional.

也许你会难过， 你会无缘无故地哭泣， 你会变得情绪化。