“Peer pressure” is a negatively-valanced term that could be phrased more neutrally as “social consequences”. Seems to me it’s good to think about what the social consequences of doing or not doing a thing will be (whether to “give in to peer pressure”, and act in such a way as to get positive reactions from other people/avoid negative reactions, or not), but not to treat conforming when there is social pressure as inherently bad. It can lead to mob violence. Or, it can lead to a simplified social world which is easier for everyone to navigate, because you’re doing things that have commonly understood meanings (think of teaching children to interact in a polite way). Or it can lead to great accomplishments, when someone internalizes whatever leads to status within their social hierarchy. Take away the social pressure to do things that impress other people, and lots of people might laze about doing the minimum required to have a nice life on the object-level, which in a society as affluent as the modern industrialized world is not much. There are of course other motivations for striving for internalized goals, but like, “people whose opinion I care about will be impressed” is one, and it does mean some good stuff gets done.
Someone who is literally immune to peer pressure to the extent that social consequences do not enter their mind as a thing that might happen or get considered at all in their decision-making, will probably face great difficulties in navigating their environment and accomplishing anything. People will try fairly subtle social pressure tactics, they will be disregarded as if they hadn’t happened, and the person who tried it will either have to disengage from the not-peer-pressurable person, or escalate to more blunt control measures that do register as a thing this person will pay attention to.
Even if I’m right about “is immune to peer pressure” not being an ideal to aim for, I still do acknowledge that being extremely sensitive to what others may think has downsides, and when taken to extremes you get “I can’t go to the store because of social anxiety”. A balanced approach would be aiming to avoid paranoia while recognizing social pressure when someone is attempting to apply some, without immediately reacting to it, and be able to think through how to respond on a case-by-case basis. This is a nuanced social skill. “This person is trying to blackmail me by threatening social exclusion through blacklisting or exposing socially damaging information about me if I don’t comply with what they want” requires a different response than “this person thinks my shirt looks tacky and their shirt looks cool. I note their sense of fashion, and how much importance they attach to clothing choices, and may choose to dress so as to get a particular reaction from them in future, without necessarily agreeing with/adopting/internalizing their perspective on the matter”, which in turn is different from “everyone in this room disagrees with me about thing X (or at least says they disagree, preference falsification is a thing) should I say it anyway?”.
The key, I would think, is to raise people to understand what social pressure is and its various forms, and that conformance is a choice they get to make rather than a thing they have to do or they’ll suffer social death. Choices have consequences, but the worst outcomes I’ve seen from peer pressure are when people don’t want to do the thing that is being peer-pressured towards, but don’t treat “just don’t conform” as an option they can even consider and ask what the consequences would be.
An observation: In my experience, when talking past each other is more difficult to resolve, it tends often to be the case that one or both parties think the other’s position is wrong morally. This appears to be the case in the example in your post, and a contributing factor in some of the conversations in the comments. If you’re on the “a betrayal has occurred” side, it’s difficult to process “but this person’s perspective is that no betrayal has occurred”, and attempts to explain that perspective may come across as trying to excuse the betrayal, rather than trying to explain a different perspective where the betrayal doesn’t exist. The betrayal, from the perspective of those who see it, is viewed as a matter of indisputable fact, not just one person’s perspective which may or may not be shared.
Many differences of perspective can be resolved with a “oh, you think this and I think that, I get it, we misunderstood each other but now we don’t, problem solved”, but “oh, you think your betrayal is nonexistent? I get it now and am fine with that.” is unlikely. Step 1 when communicating across this sort of difference is to communicate to the person who doesn’t see the moral wrong, that from the other person’s perspective, the issue is a moral one. Once that has been successfully communicated and the situation de-escalated, the other perspective where there was no moral issue at stake may be more likely to be communicable to the person who didn’t hold it originally.
It’s a weird thing about humans, how our thinking can flip to a different mode when we perceive a moral wrong to have occurred, and that when we’re in the “a morality-relevant thing just happened/someone did something wrong” mode it is hard to take the “but other people may not see things the way I do” step. I could mumble something about this having evolutionary roots to do with coordination among groups, but I don’t have a good story for why we are this way, I just know we are. And: It doesn’t require a traumatic past experience with betrayal, to flip into the moral mode when you see a betrayal happening, and then react poorly and (from an outside perspective) unreasonably if other people don’t see things your way. I for one was raised to believe that when my “conscience” is activated by a moral wrong, that “conscience” is universal and every good person would see things the same way. This is factually incorrect, but seems very strongly like it should be right intuitively at times, particularly when having a reaction to something I see as wrong.