I think expressing emotion is important, but more often than not verbally expressing every emotion and disappointment is not only tedious, but it's downright tiring. Instead, when I have an issue with someone or something in particular, I try to run it by someone whom I trust (a close gal pal, sponsor, etc..) just to check my own actions and recognize that I am human and can be overly sensitive. If I receive validation that my emotions are pretty on-base then I may or may not disclose my certain comlaints towards the individual I'm struggling with.
It also depends on what kind of problem I'm having and who it's with. For example, if I'm having a disagreement with a close friend, you bet your bottom dollar I'm going to try to resolve that a.s.a.p. because I really care about the relationship. However, if it's with a repeat offender (new guy, old enemy, etc..) i'm more likely to either let it blow over or just start distancing myself from them.