In my parents' day the lyrics to a popular song said, “You always hurt the one you love - the one shouldn't hurt at all.” It's inevitable that if we're in a relationship - we're going to hurt our partners' feelings eventually. We watched our parents do it, we did it with brothers and sisters and friends - but we didn't always witness good techniques to fix the damage done by our careless words. We might optimistically tell ourselves that they'll get over it…but is there a better way to open up a person's spirit that we've closed down? I've got a couple thoughts on the topic of healing a wounded spirit.
As usual I'll suggest different things to do for each gender.
Women often don't realize they hurt men's feelings because men may stuff strong feelings and become stoic; or they may show anger when they experience strong feelings like fear, disappointment, or sadness. This can be confusing for women but if he's unusually withdrawn or angry for no apparent reason following an interaction with you then approach him and quietly mention that you're sorry you had words earlier - that you love him and hope he'll feel better later - then leave him alone so he can let go of his strong feelings by himself.
Men, most of whom know well how to leave an upset man alone, will mistakenly do the same with an upset woman. When your female partner is upset, move to her slowly and softly, touch her in a non-sexual way and gently tell her how sorry you are that you were so mean and that you really hate to hurt her feelings (I try to do this even if I thought my wife was just as mean as I was). If you're lucky, she'll respond by giving you both barrels. I say you'll be lucky because if she can get her negative feelings out now then she'll feel better and credit you for helping. If however when she blasts you, you argue with her then she'll tend to keep her negative feelings - believing you didn't hear-care-or understand her, and you'll hear about them again later.