Couples sometimes have disagreements and that's perfectly normal. What's important is to "fight right".
1. Communicate your feelings
One way is to ask "Why?". Find out your partner's POV of the issue in order to fully understand the cause of what is upsetting to them. A disagreement is not one-sided, so it is also important for both of you to have a voice in expressing how you feel. After this communication of feelings are done, discuss or propose a solution to the problem. Remember, it might be convenient to, but don't sweep things under the rug!
2. Embody the good traits you want in a partner
Repeat after me: To find the one, you have to be the one
It is often easier to see the faults in someone else, compared to our own bad traits. Do you react to some conversations passive aggressively? Are you finding ways to incite jealousy?
These back and forth interactions may cause a toxic dynamic to form, and you might realise that the both of you are treating each other with less love and respect.
Confronting our own toxic patterns, and being the partner we want to have, can go a long way for a blissful relationship. You can do it!