Your relationship becomes a third entity between you.
Your relationship is very much like a new born baby, it needs to be fed, it needs to be nurtured, it needs to be wrapped up in a warm covering of safe secure attachment, and it needs to be kept safe from anything that might try to harm it.
Your relationship will mature, but will always remain like a new born baby. Like a new born baby, it will never survive by itself without constant care and attention. It can never be taken for granted.
Just like a new born baby it will occasionally become distressed. Just as you cannot leave a baby distressed, as soon as practical you need to repair the relationship. You need to hold the baby, reassure the baby that it is safe. Similarly you need to hold your partner, reassure your partner that the relationship is safe, secure, supported and cared for.
If you are the offending party, repair is achieved by listening at an emotional level, empathising and having compassion for the other’s wounded attachment - without competing with your own emotional wounds. Both members of a relationship are often hurting at the same time, but repair is achieved by empathising with your partner’s wounded feelings. Your partner needs to feel Heard, understood, and receive empathy for their emotional experience. Logic, explanation or justification will send the message you are not listening only defending. Emotions are not logical but are perfectly understandable if you truly listen.