I was just chatting with a friend, and was reminded of a value that's really important. Everyone should start every conversation with a clean slate with the other person. If you're holding a grudge of any kind, ideally, that's been aired, and heard, and dealt with. I know this is an ideal, but the closer you are to it, the more value there is in the friendship.
If you can get through years of hanging out with someone, and yet still at the beginning of every interaction you can say the slate is clean, then you really have something.
It also works for people you've never met. If you let other people's grudges interfere with your perception of someone else, then you're not going to have the best interaction possible. The more the grudges color things, the more you're interacting with the grudge, and less with the real person, who might not even have any knowledge of it!
Often, people don't bring their problems with other people to the person, they spread them around behind their back. You shouldn't let that kind of gossip interfere with your potential relationship. Again, that's an ideal to strive for. We're all human.
On the other hand it means you have to be ready to hear from someone about something they feel wronged by. And after that if they can say "it's now been dealt with" you can get back to being buddies.
The behind-your-back part of it can be really insidious. A couple of times people have asked me "Why does everyone say you're a dick." If that happens to you, please -- you do not have to respond to it. Or respond by pushing your glasses down your nose and look at the other person and say "Really?" Try an eye-roll. You are not responsible for the grudges people spread about you.
Also, many things that become grudges are really not worth worrying about at all. Remember how small we are and how short life is, and ask yourself if you can just let this one go, and not get full acceptance from the person who hurt you. Maybe this is a person who's worth it.
I tried an experiment a few years ago. Someone who had hurt my feelings came up in conversation with someone else, in public. So I said the other person was a very generous, wise and sweet person. Guess what happened. That's exactly what they turned into! I never got "closure" on the perceived offense. I'm sure had I confronted the person it would have just deepened the wound, for both of us. Instead, it was put aside, as an experiment, and something really interesting blossomed in its place. No regrets.
The point is this -- the resolution can come from you. You don't have to wait for the other person to give it to you, in order to get back on the "good friends" track. But there are other related lessons, and you always have to keep your eyes and ears open, and memory is important -- you should watch for repeat behavior. But it is possible to move on from a hurt without a confrontation. It often is the only way.
The people I admire most are the ones who I am sure have never had a grudge with me. I can think of a few such people. I never have to worry that I need to clear the air. Those people are what I think of as best friends.
PS: This idea was expressed in a more light-hearted way in a piece I wrote in 1995. Scroll down to the heading "A new form of social behavior." I attract a lot of hate, of course I know it. I can hear their voices in my head, as I write something that people will object to. I guess part of who you are is determined by what you do in response to those voices. Too often I give into them. When I was first starting out writing on the net, I wasn't so familliar with the voice, so my writing had a breezier more fun style to it. The hate grinds you down. I don't know how to avoid it. But I wish I could.