[afro88]

Being vulnerable only builds trauma if you're being vulnerable to damage that you aren't prepared to handle. Otherwise it's "just" adversity that you can overcome with support from close friends, family and/or a therapist, as well as what you have learned (books, courses, podcasts, lived experience etc). The former being the healing, the latter being the processing. The more adversity you overcome, the more resilient you become.

I would also say, don't rule out being a little vulnerable with people before you intend to become very close to them. Firtly, doing it in small doses at first and overcoming the damage will build some resilience before you meet someone new that you intend to be very close to. And secondly, often you won't know you want to be very close to someone until your connection with them is stronger and you know them well, and this can't happen without some vulnerability shown by both sides.