You ever look across the living room at your partner and think, "I know everything there is to know about that person"?

Careful. According to relationship therapists, that kind of thinking could be one of the biggest mistakes couples make.

People change over time. Your partner's favorite food might have changed, their hobbies might be different, and that thing they used to find hilarious might now get you nothing but a look that says, "Are you seriously still doing that?"

Here in Michigan, we know all about things changing. One day it's 75 degrees and sunny, and the next you're scraping ice off your windshield in October. Relationships can use a little weatherproofing, too.

Here are five mistakes couples make without even realizing it.

1. Thinking You've Got Your Partner All Figured Out

Just because you've been together for 10, 20, or 30 years doesn't mean you've unlocked every level of your partner.

People develop new interests, change their minds, and discover things about themselves. Keep asking questions and stay curious.

Maybe your husband suddenly wants to try yoga. Maybe your wife has developed a passion for fishing. Maybe the person you've known for years has a secret dream of moving to a cabin Up North.

Don't assume you know everything. You might be surprised by what you learn.

2. Avoiding the Tough Conversations

Money, intimacy, household responsibilities and future plans aren't always fun topics. Neither is figuring out why one person thinks the thermostat should be set to 68 while the other dresses like they're preparing for an expedition to the Upper Peninsula.

But avoiding difficult conversations doesn't make problems disappear. It just lets them sit there and get comfortable.

Talk honestly, listen without turning every disagreement into a courtroom trial, and try to solve problems as a team.

3. Focusing Too Much on What's Wrong

It's easy to notice what isn't working in a relationship. Maybe you're not spending enough time together, romance has slowed down, or your idea of a big night out is wildly different.

But therapists recommend paying attention to what's going right, too.

Compliment your partner. Tell them what you appreciate. Focus on what makes you feel connected instead of treating every little issue like a repair job on I-75.

Nobody wants to feel like they're getting a performance review every time they walk through the door.

4. Getting Stuck in Maintenance Mode

Life can turn into an endless checklist: work, groceries, laundry, bills, dinner, repeat.

In Michigan, you can add shoveling snow, mowing the lawn, raking leaves, and wondering why the same pothole keeps destroying your suspension.

Before you know it, you're less like a couple enjoying life together and more like two coworkers managing a household.

The solution? Make time for something different.

Try a new restaurant, take a weekend drive along Lake Huron, visit a cider mill, or plan a spontaneous trip Up North. It doesn't have to cost a fortune. Sometimes, just doing something together that isn't another chore can make a difference.

5. Keeping Your Good Feelings to Yourself

You might think your partner already knows you love them. And maybe they do. But hearing it still matters.

Tell them you appreciate what they do. Thank them for the little things. Give them a genuine compliment that doesn't involve asking where they put the remote.

A simple "I'm glad we're doing this together" can mean more than you realize.

Don't save all the nice things for anniversaries, birthdays, and Valentine's Day. Your partner shouldn't have to wait for a greeting card holiday to find out they're appreciated.

The Bottom Line

A strong relationship isn't about knowing everything about your partner. It's about staying interested in the person they're becoming.

Ask questions. Have the difficult conversations. Make time for fun. And remember to say the nice things out loud.

Because whether you're spending a romantic weekend in Traverse City or arguing over who left the empty Vernors bottle in the refrigerator, the little things add up.

And if you really want to keep the romance alive in Michigan, here's one final piece of advice: Never forget who volunteered to drive when the roads are icy. That's true love.

Based on relationship advice reported by the New York Post.