Lack of trust can be present in a friendship, too. It’s possible to feel closed off and guarded around certain friends, says Licuanan. One potential sign on a toxic friendship is a feeling of being guarded or closed off—for example, the lack of ability to be your authentic self around that person or the desire to withhold what you share with that person. You shouldn’t have to feel the need to distance yourself from someone, adds Licuanan.