James react the most calmly. He gets that humans can sometime experience hormonal changes that cause their moods to constantly change. He would try to calm her down if she’s angry, encourage her if she’s down. He’d be most supportive. If it keeps happening on an unhealthy level, he’d take her to a psychiatrist.
Erik would also be mostly calm. He might also believe he did something to trigger this and ask if he did something wrong. He’d hug her if she’s sad, or let her take out her anger on him if she’s angry. He’d give her a massage and prepare a nice, hot bath for her.
Sam is absolutely clueless about what he did wrong when she suddenly starts yelling at him out of the blue and then start crying before he even gets a chance to open his mouth. He panics, thinking he must’ve said something wrong. He fumbles with his word and panics even harder when she starts crying even harder. He calls all of his brothers and their wives, but they’re not much help. He eventually picks her up, throws her to the bed and hugs her to his chest. They stay like that until she calms down.
Matthew is also quiet confused when she starts changing from laughing to crying, and crying to absolutely livid in a time span of 10 seconds. At first he just sits and watches her laugh, cry and shout. Then he gets up, grabs her and sits her ass down on the couch, and brings her some hot chocolate from the kitchen. And it works. There’s nothing a good hot chocolate can’t solve.
Damien is not even startled in the slightest. He knew it was coming. He just talks to her, lets her hit him in the chest, or cry on his shoulders. They talk for hours until they find the problem causing these mood swings, and find a solution.