I have a friend (we'll call them Dallas) who gets frustrated very easily. Not mad, perhaps, but frustrated and short-tempered as a result of some minor incident.
A recent example is that we went to a bar to celebrate a friend leaving our city (goodbye party of sorts). Dallas had to take a rideshare back home, which costs about 8€, around 11 PM because they had to work the next morning. Dallas asked if any of their roommates were going back with them, but nobody was since we were staying out. Dallas was under the assumption that someone was going to split the cost of the ride, before we went out. So having to pay the full amount by themselves was frustrating. After a few minutes of asking around they became annoyed/visibly mad because they had to pay for the ride alone.
This would be understandable, except that another friend offered to pay (entirely) for their rideshare so that Dallas didn't feel burdened financially. Dallas didn't seem to care that someone was willing to pay for the ride, instead they stormed off and waited for their rideshare alone.
This is the most recent incident of short fuse with Dallas. Dallas is very high-strung and get frustrated and angry easily. There have been other far more minor incidents in which Dallas gets angry and walks off/storms off.
I'm a very chill person, so this kind of behavior makes me uncomfortable in that the situation escalates from nothing (or a very easily-solvable problem) to something that's "the end of the world". How can I tell Dallas to "chill out", to stop taking things so seriously and/or to let others help resolve their frustration (as with the rideshare issue)?
Overall I really like Dallas, but their short temper is difficult to manage. I'm not the only one in our group of friends who feels this way.