Why Does this Keep Happening in Conversations

Every week or so my partner and I discuss something and I always end up saying something that pisses him off or hurts his feelings.

most recently it was about a video game, where you need multiple people to play and his friends are flaky. He mentioned he met a girl on a discord server for this game and i said 'I may be very territorial over you icl' because I have never met this girl.

this caused a lot of issue and he is now 'cooling off' and I honestly don't know what to do, I don't want to lose his trust and love.

We are always fine in person, but never on text, so I don't know if maybe i just suck at messaging or if I am genuinely not good for him...