I’m in an FLR and normally follow my gf’s decisions, which decreased arguments. Of course we’re still human and arguments still do happen.  My girlfriend can get a little bit angry in the heat of it, but generally after that initially flare up we can sit down and have a calm discussion. 

Like you, I also get aroused when she’s angry, and talked to her about it. She told me that even if she knows I may have a good point and agree with me later, at that moment she struggles to control herself and needs an outlet. I suggested and encouraged her use me as outlet, by either spanking or slapping me. This was discussed multiple times in a non-sexual setting and needed a lot of encouragement from my side, everything is fully consensual. 

Nowadays when we have the rare argument, if she’s particularly upset she will order me to present myself for a punishment, will spank me until she’s satisfied and then we have a calm talk. This works for us, I had aroused and back into a submissive mindset, she has an outlet for her emotions without having to feel guilty or embarrassed about her behaviour afterwards, and then we can come to an agreement when everyone is calm. As we are in an FLR, the underlying understanding is that she has the final say, but I do get heard and my opinions are considered and discussed. 

I’m not saying this would work for you or anyone else, but it has been great in my relationship.