"I Just Said What I Think": When Blunt Truth Lands Like a Punch

They gave you their opinion with no softening and no checking, the true thing said the blunt way, and then looked genuinely surprised when it landed like a punch. "I was just being direct." Yes. Direct like a scalpel in a room that needed a bandage.
One of you equates truth with bluntness. If it is real, you say it straight, and wrapping it in padding feels like lying. The other needs the padding, not because they cannot handle truth, but because delivery is part of the message. A truth thrown at you hurts differently than a truth handed to you. The direct one decides the sensitive one is fragile. The sensitive one decides the direct one is careless. Neither read is correct.
This is the low-warmth end of Agreeableness meeting a partner higher on it, the Cooperation facet that governs how much you factor another person's comfort into your delivery. A person low on it treats feelings as the property of the one who has them, so managing the wording is not their job. A person higher on it treats feelings as shared, so how a thing is said is part of what is said. Same fact, two theories of whose responsibility the impact is.
"I just said what I think" is less a defense than a confession. It means "I do not yet know how to say hard things gently." And "you hurt me" is not an overreaction. It means "the delivery did more damage than the content did." The fix is trading one habit each: the blunt partner adds a sentence of care before the sharp one, and the sensitive partner names the delivery rather than swallowing it, so the truth can arrive without the bruise.
You can see where each of you lands on Agreeableness and its warmth facets with the 30-facet OCEAN personality test. It takes about 15 minutes, the domain scores are free, and a compatibility report shows whether "I just said what I think" is a values clash or only two people disagreeing about who owns the impact of a hard truth.