It's like riding a motorcycle. You're not wearing gear for IF you go down, but for for WHEN. It might not be exactly this moment, but it's coming regardless. Women will always try to feminize even the most macho of men to see how much they can bend them, but the second he bends to her will she loses respect for him and loses attraction. Even if it's "her idea" for you to make yourself vulnerable, she will hold it against you. Deep down, even the most redpilled men have a purple-tainted heart and want to be loved for who they really are inside, so sadly even the most vigilant man can be caught off guard. I've done it and bet you have too, where you unicorn at least one woman, and you can't help but let down those walls. No matter how amazing you think she is, she's still a woman.
We've had bad things happen to us. Maybe we were raped, molested, assaulted, etc, and we feel safe enough to confide in our significant other. Feeling safe is different from being safe. Inside, she's turned off by this happening to you. She knows it's not your fault, but she can't help but lose respect and lust for you. She longs for a man who shows his emotions/feelings to her but wants to toss him out when he does. You are damned if you do and damned if you don't. The second you show her your heart, she'll make a note to stomp it into the ground.
It's not your fault, but never let her know about your weaknesses or show your flaws. You won't be the exception.