There's a lesson anyone can learn from couples who are in arranged marriages

Love, he said, is a commitment. There will be mornings when the kids are screaming, and the dog needs to be let out, and your partner is hogging the bathroom, and you're not exactly feeling "in love" — and still, you stay with your partner because you've agreed to love them.

It was hardly the most romantic image he could have painted, and maybe that's why it's stuck with me since then. I thought about his words again this week, when I spoke with Pamela Regan, a psychologist at California State University, Los Angeles who studies romantic relationships.

Regan and her colleagues published a paper in 2012 with findings that surprised even them. After comparing Indian-American individuals who were in arranged and love-based marriages, they'd found no difference between the two groups when it came to commitment, love, or marital satisfaction.

Regan was careful to caveat that all participants in her (relatively small) sample were educated and highly assimilated to life in the United States. The same findings might not generalize to people of different socioeconomic status, living in other countries.

But that research helped shape her view on relationships today:

"I think of [relationships] as being on a sea, like waves. They go up; they go down. Things like passion, things like desire, things like romantic love and satisfaction — the good stuff, the positive, the warm fuzzies that we seek to find in our relationship — these things aren't absolutes. They're not there or not. They are more or less, depending upon the day."

It's something that couples in arranged marriages probably understand, she said. Presumably, they don't feel much passion, desire, or romance at all when they first meet their partner — but they know that those feelings can develop.

Indeed, research by the psychologist Robert Epstein and colleagues found that love does grow over time in arranged marriages.

Regan suggested that it's easy to leave or give up on a relationship prematurely. She's not advocating that people stay in unhappy or unfulfilling relationships — there's no shame in calling it quits.

But if you and your partner are having a rough day, or even a rough few months, that doesn't mean there's something wrong with your relationship. It's worth remembering that sea metaphor.

If you hold fast to the belief that, "when I find the right person, I will always be happy; I will feel passionate desire for this person always," she said, you're pretty much "doomed to disappointment because life isn't like that."

Again, it's not the most romantic insight. It's easy to believe that your relationship will be different — the one where the spark doesn't fade over time, as psychologists say it almost always does.

Because arranged marriages tend to be more about the needs of the families than the individuals, Regan said, people generally stay in the relationship.

Obviously, this isn't always a good thing — but what those couples know that everyone else could use to learn is: "Even when maybe passion isn't very high, they don't leave. And what they may find is that it comes back."