While relationships take time to cultivate, unfortunately they can be destroyed in an instant. As graduation approaches, emotions are running high, and sadly, I've witnessed many avoidable falling-outs.
Cut your friends slack and remember that transitions are stressful. Try to avoid unnecessary one-on-one situations with people that you might have lingering tensions with. It's better to leave on a positive note than to chance an emotional over-reaction that'll be hard to resolve online or over the phone.
Don't let small tensions ruin an otherwise joyous occasion. Graduation should be a time for cohesion not division. Especially if you're no longer going to be seeing each other on a regular basis, then it's probably best to just let bygones be bygones. But, if issues need to be addressed, do your best to hold off on any discussions until everyone is level-headed.