“The quality, not the longevity, of one’s life is what is important.” -Martin Luther King, Jr.
While knowing someone for an extended period of time does help to know that person, it does not weigh heavily in terms of the relationship that the two of you share. What truly matters is the effect that the person has on one another.
For example, you had just finished a bad day, and your friend/partner sees your distress. Do they take their time to see that you are well, or do they look the other way? Being in a relationship of any kind means that you and the other person are there for each other, for the good, sad, and terrible days.
The two, or more of you, can rely on each other if a problem arises, and can give advice as well as comfort to get you through the day and conflict. What is the use of knowing someone when you don’t keep constantly talking to them, checking on them, or even to hang out with?
If anything, the quality matters as it shows how true of a friend or partner they are towards you, which is really important in life. It is a part of happiness, and we all deserve that much, to ourselves and each other.