When it comes to dealing with processing emotional flare ups (the negative ones) with a friend or partner, I think it is important to be able to allow yourself to feel that emotion and then authentically explore the cause within yourself.  Having a partner that can understand this need and also not internalize that reaction as a personal reflection on them can go a long way.  More often than not, when we get upset, it isn’t really because of someone else’s actions (in a relationship setting), but more so because somewhere deep inside of us, there is an unsettling reflection happening on ourselves.  It is up to us to find it and then decide if it is true or not.  Having an emphatic partner or friend can help quite a bit with this.