This pounded into my head that I must be perfect or people won't like me. So now when a flaw pops up or if I get even a hint that someone has a problem with me, I'm outta there like greased lightning.
This has been an issue for me too, and still can be if I'm having a bad day, am triggered or just a bit tired.
I need to never get anything wrong, or have needs or wants or anything close to making demands in relationships, and I need to be whatever the other person wants me to be, perfectly. And if I miss any of that, or think I might have missed it, it feels life threateningly dangerous, so I respond by fight or flight. I don't know your background but for me this was borne out of parental relationships that were very frightening, violent and unpredictable where I grew up thinking all relationships are like that.
So, I've been known to have a complete meltdown because someone couldn't do something I had asked them to, because in my head they couldn't do it because I should never have asked (so got it wrong). Or because someone asked me to do something differently, or because I couldn't find a freshly laundered dish cloth for them (seriously), or they wanted a particular kind of tea that I didn't have... you get the general idea.
Now if I find myself having an emotional response that doesn't correlate to the actual situation, I know I've been triggered, so, instead of hitting the destruct button, I'll take some time out, try to ground myself, cry, whatever but I don't act on my feelings with the other person until I'm grounded and know what it is I'm actually responding to.
I wonder if your relationship stuff might be triggering you too without you even realising it? It took me a long time to recognise that's what was happening for me - as in 2 years in therapy - but once I realised that was it, I've been able to treat it like every other kind of trigger and things have got easier in terms of relationships.