So I will go out and assume it is possible your girlfriends are all normal. In this case it would mean the emotional outburst are natural mood swings that are amplified.
I have said a lot of people look to their surroundings to know how to act and be normal.
Baby A: The first baby falls hard and looks around. It comes to the mother’s attention and she rushes over screaming all worried. It brings the baby too tears because the baby thinks it should be reacting more. From that moment on the baby cries when it falls.
Baby B: The second baby falls hard and looks around. It comes the mother’s attention and she just smiled before picking the baby up while saying whoopsy daisy. It brings the baby to keep playing despite the mild lingering pain from the initial fall. From that moment on the baby just gets back up when it falls.
I think if this is the case there are ways you can help her be calmer day to day. I would suggest never ever telling a girl to calm down. I will tell you right now the best response you can get from that is the women concealing her feelings and growing in resentment and anger. It will be subtle though she will feel more and more alone and it will worsen the outburst. I find the best way to handle the situation is to deescalate the situation.
From time to time just pretend you understand (even if you do not. It could be she just wants someone to listen to her and she is being dramatic to try to hold your attention. I would like to remind you to only do this sometimes so she does not feel alone. Reinforce stuff like…
“I totally understand I have feel the same sometimes I just have trouble expressing it!â€
“I can’t believe itâ€
“I know right!â€
For the part where you want to persuade her to be calmer I suggest reinforcing it. So when you see her being calm. Reinforce stuff like…
“I like it when you act so mature and level headedâ€
“I love how you behave so much like an adult unlike others honeyâ€
“I am so seduces when I see you relaxing let me help you ease up rubs backâ€
“It is so hot when you are emotionally stable and in control of your emotions and I want you to use that same level of control on meâ€