Generally things like "self disclosure", "trust" and "commitment" are things that are highly correlated with strong friendship quality. I loosely put all of tho

Generally things like "self disclosure", "trust" and "commitment" are things that are highly correlated with strong friendship quality. I loosely put all of those under the umbrella of vulnerability as self disclosure and trust in particular generally mean you allow someone to use the information given for bad reasons potentially. Here's a good starting point. http://journals.sagepub.com/doi/abs/10.1177/146144804044331 http://journals.sagepub.com/doi/abs/10.1177/146144804044331