Listen, really listen to them. Put yourself in their position and really empathise with them. Remember and reaffirm regularly that you are a team and that you both have the others interests at heart, you should be one unit against the world.
If you get mad or argue, apologise, it doesn’t matter who is right, you’re apologising for upsetting them.
Do things together, and separately, share your experiences.
Try and eat facing each other when you can, with all the screens around it can really be easy to forget that face to face contact.
Never go to sleep with unresolved issues, don’t be afraid to be honest about why you are upset, and make them feel comfortable doing the same.