We all have habitual patterns, ways that we prefer to do things. When we get locked into them, when we're unable to do things another way or to accept deviations in the patterns, we suffer.
When we're in relationship with another being, each person has their own habits, often interlocked with the other's, and the relationship has its own set. Meanwhile, the relationship (and the people) operate in the larger society, which has its own rules and expectations, its own pre-dug ruts.
In Buddhism, we try to approach every moment with beginner's mind, not with jaded we've-been-here-before mind. That mind says, You never take the garbage out. We always hang out with your friends. You looked better when we met.
Beginner's mind says, instead, look at this being across the table from me, full of feelings and experiences. Who is this person, who has sat across from me all these mornings and evenings? What, in this moment, do I truly appreciate about this person? Can I see that this is another being, not simply an extension of my habits?
Shared history, shared culture puts a heavy sweater of experience and expectation on each person. What does the tender and dear person under there look like without the layers?
What would you say if you didn't think you already knew how your partner would answer?
I defer to the master, Tom Waits:
You wear the same kind of perfume
You wore when we met
I suppose there's something comforting in knowing
What to expect.
But when you brushed up against me
Before I knew your name
Everything was thrilling
When nothing was the same
I want you to kiss me
Like a stranger once again