We are all familiar with the conventional wisdom (backed by research) that you need to really know who you are as a person before trying to love others.

But being totally set with your own identity isn't only unrealistic; it's unnecessary. The best sign you're in a solid relationship is that your partner is actually making you a better person. And according to science, that's totally possible.

A good partner pushes you to be better: A 2014 study published in the journal Personal Relationships looked at how being in a relationship affects a person and their self-perceptions. As it turns out, relationship partners can encourage one another other to "realize aspects of their ideal self," pushing them toward their goals and helping them grow in ways they've desired.

This process is called "self-expansion," and psychologists argue it's part of an innate human drive to connect with others in order to improve ourselves as people. According to the study's lead author, Brent Mattingly, self-expansion not only means recognizing your S.O.'s positive traits, but really taking them on.

"We actually incorporate some of our partners' traits into our own sense of self. If my partner is a very charitable person, I may begin to become more charitable as well," Mattingly told Mic.

That change, the study found, actually positively affects our self-concept, i.e. how we view ourselves as people. As the study's authors write, "A person who acquires an appreciation for the ballet or becomes a better painter from being with a romantic partner would experience an increase or augmentation of his or her self-concept." That's a very good thing.

They downplay our negatives: Significant others aren't just filling up our ego tanks — they help cut back on the negatives through a complementary process called "self-pruning." This occurs when we rid ourselves of some of the not-so-desirable qualities we all possess.

The self-pruning can be prompted actively, as Mattingly explained: "If I want to reduce the amount of junk food I eat, my partner can help facilitate this by providing me the emotional support to pass over the French fries and instead reach for the fruit."

Alyssa, 31, told Mic that her husband "reminds me to stop stressing about the little things" that would get in the way of her enjoying their relationship.

Self-pruning doesn't need to be the result of direct criticism or nagging (which can be a pain). Rather, it can happen inadvertently, as the study authors describe: "An individual's bad habit (e.g., talking too loudly) may develop into a social allergy for a romantic partner. As a result, the romantic partner may help the individual break (or at least weaken) the bad habit."

Getting better all the time: In unhealthy relationships, partners have the potential to pollute each other's sense of self and adopt more negative qualities. But happy, healthy couples are the ones who make each other better by sharing the best qualities they have to offer.

The idea of "changing for your partner" gets a bad rap; but in truth, our relationships are changing us all the time — often for the better.