That would seem like a reasonable supposition, but it’s not, given how much men tend to project their own values and beliefs onto women and assume they feel the same, I'm going to bet that overwhelmingly these men have not had any experiences of women reacting negatively to their vulnerability - they are just passing along how they imagine women feel and then blaming them for that.

https://www.doctornerdlove.com/episode-144-use-this-mindset-to-overcome-your-self-limiting-beliefs/

“These are all anxieties men have about themselves, anxieties that they are externalizing and projecting onto others. They are, in effect, taking things they dislike about themselves or beliefs they have about their own value or worth and turning them into universal rules.

Instead of addressing the root issue — insecurity, body issues, societal messages about “real men” — it’s easier to project it onto other people, make it their fault. It becomes a way of excusing yourself from even TRYING; it’s simply a law of the universe, so what’s the point?”

You're in your first romantic relationship, so clearly you've not had that happen to you in other relationships because there haven't been any - and yet you felt fine passing along this kind of "just so story" as if it were a prevalent belief amongst women — when I’ve already quoted to you statistically how it’s not.

For example, many men are sure that what women care most about in a partner is their looks, because that's what most men care about - but there is overwhelming evidence that this mostly isn't true for women.

https://www.menshealth.com/sex-women/a19535604/top-20-traits-she-wants/

"Recent online surveys of more than 1,000 women between the ages of 21 and 54 (one was conducted by Princeton, New Jersey’s opinion Research Corporation; the other was done on BestLifeOnline.com) found that women value personality far more than physical attractiveness. What women want in a man is faithfulness and dependability, a sense of humor, the ability to listen, and a sense of style. Only 13 percent of women cited muscular build as a factor in physical attractiveness. On the other hand, 66 percent of women said moral integrity will “make me quiver.”

https://www.theguardian.com/news/2004/apr/22/thisweekssciencequestions.evolution

"Personality had a much greater effect on women's perception of good looks than men. "It's quite remarkable how little women are influenced by physical looks. All men should pay attention to this. It's much more important to be a valuable social partner than worry about your physical looks," says Wilson.

The effect can work both ways. One 50-year-old woman rated a boy who was in her high school yearbook as extremely ugly. "We couldn't understand it, because he looked so average," says Wilson. "When we asked her why, her face contorted with disgust as she explained what a foul-mouthed jerk he was. It was nothing to do with his looks."

It's not enough to just be "nice" - you've got to have some sense of personal style, some inner confidence, etc., but it doesn't seem to matter to some guys how many women say this and how much research there is to support it - because they'd rather tell these kinds of just so stories that allow them to scapegoat women. That's what I'm reacting to in my comment.

https://www.elitedaily.com/dating/3-reasons-looks-dont-matter/979150

"I’m not talking about social status as in fancy cars or gigantic Hollywood mansions. What I mean by social status is social intelligence. Women are innately attracted to men who are socially skilled.

Guys who can make women laugh, act confidently around them and communicate effectively with them are the men who have high social status."

Yes, there are some women out there who have a lot of internalized patriarchy and expect men to be stoic and not show vulnerability, but they are increasingly in the minority, particularly amongst younger women. In fact, many younger women have said they’d rather have an emotionally expressive partner than just about any other quality. So, it’s fine to note that some women feel this way, but making it out to be a near universal expectation is both counter-factual and counter-productive.