I mean, it's one thing to be sensitive but that seems like an excessive amount of getting upset on a regular basis. Unless she's actually seen a psychiatrist or therapist before I wouldn't immediately rule out some sort of imbalance, may it be depression or not. There's all sorts of mood disorders out there, and if she starts to cry at the littlest inconvenience that means that her moods aren't very stable. You say that these crying jags can continue on and off throughout the day- hormone imbalances can also put your body out of whack, where these emotional outbursts are just bubbling waiting for something to give them permission to bubble over.

Maybe she was an only child or the youngest and used to getting negative attention like this from her parents. Even if you guys have a good relationship, sometimes people revert back to immature, childlike behaviors when they are in a relationship with someone they trust. She's getting her needs met when you jump into caregiver mode, which isn't fair to you, bc being around someone who is so fragile that even simple things like filling out a form can ruin their entire day is a bit much.

You cannot walk around on eggshells avoiding confrontational conversations simply to spare yourself even more tears on her end. If she's crying all the time, you're going to have to cope with it anyways, so you might as well get this stuff off your chest before you end up resenting the relationship enough where you are just done with all of it. Whether you suggest she see a doctor to check her levels, or a therapist to teach her some actual coping skills, something's gotta give!