But they aren't. Act like an adult means - if you have problem with something, say it. Talk to fellow player, talk to dm. If someone says or does something that upsets you, voice it out.
A close friend of mine told me the other day about some books she's been reading about communication styles that people have. Apparently, two of the most common types are (if I remember the terms correctly) "speaking" and "signalling."
In the scenario where a person is trying to get a jar from the top shelf, only to find that it's out of reach, a "speaking" person will turn to someone taller than them and ask "can you help me get this?"
A "signalling" person, however, won't make such a direct appeal. Instead, they'll make their struggle obvious by standing on tiptoes, groaning with effort, making repeated attempts, etc., all within someone else's line of sight. It's their way of indicating that they need help without actually
saying that they need help.
According to what I was told, people who use this latter form of communication don't see it as any sort of personal fault or something that they need to change. To them, signalling is more preferable to speaking out (I'm not clear on why; if I recall correctly, it can range from shyness to preferring to be circumspect). If other people don't correctly interpret their signals, it's often taken to be the non-understanding person's fault, because how could they misread something so obvious?
I bring this up simply because the issue of not speaking up when something you don't like happens isn't necessarily a case of "not being an adult." Different people have different personality types, and some people are simply more inclined to be less verbal in how they broadcast their emotions. It's true that people aren't mind-readers, but that cuts the other way in terms of having awareness about how people are reacting to what's going on.
Of course, tabletop RPGs have long had a (justifiable) reputation for attracting people with poor communication skills and/or trouble reading non-verbal cues, so in all honesty this seems like the hobby that's most ripe for that kind of misunderstanding anyway.
I'm personally not a fan of "safety tools" in RPGs, as I think it presumes that playing those games inherently carries a risk of being "unsafe," but at the same time I think there needs to be a more nuanced approach to people being uncomfortable with something than "it's your problem, you deal with it" (which I'm saying in general, rather than attributing that sentiment to you personally).
