Difficulty Trusting Others
You want to let someone in, and some part of you does. But there's another part that's already bracing, already scanning for the moment they'll let you down, already half-expecting the good thing to end. It can look like needing constant reassurance, or the opposite: staying just far enough away that no one gets close enough to hurt you. Either way, it rarely feels like a choice. It feels like common sense.
Distrust like this is usually earned somewhere. Maybe by someone who said one thing and did another. Maybe by a home where love came with conditions, or where being vulnerable was met with ridicule instead of care. Once that lesson is learned, it tends to generalise: the specific person who broke trust becomes evidence about people in general, and the nervous system stops waiting to find out if someone is actually trustworthy before it decides they aren't.
In therapy, we look at where the guardedness was built, and what it was protecting you from at the time. Often it made complete sense given what you were working with. The work isn't to convince you to "just trust people," which rarely holds up under pressure. It's to help you tell the difference between real warning signs in front of you and old alarms going off out of habit, so trust becomes something you can extend deliberately, rather than something you either give away too fast or refuse to give at all.
Over time, this tends to open up a different kind of closeness: one where you're relating to the actual person across from you, not to a version of them shaped by everyone who came before.