If you are dismissive towards your partner there are some things never to say, such as personally attack them or curse at them.
If you are usually accusing your partner of wrongdoings that are actually your fault, this is one of the ways you're invalidating your partner.
It is extremely hurtful to cut off your partner when they're speaking.
This is a terrible type of emotional abuse and can make your partner nervous to talk to you.
This is terrible emotional abuse and can quickly destroy your relationship.
If you are angry at your partner, tell them your feelings and why you are frustrated instead of blatantly ignoring them.This is one of the most hurtful ways you're invalidating your partner.You are expressing that you don't take them seriously and their feelings are insignificant.This may be due to some type of psychological abuse in your childhood but it is not right.If you bring up events in the past that should be forgotten this is one of the ways you're invalidating your partner.
If you are angry at your partner for something you should talk to them nicely and respectfully instead of wrongfully threatening them.