Dr. Jory says that when you are trying to manage it all, you don't always show your best selves. "Typically, couples also have to manage 'the extended family' over the holidays," he points out. "This can mean dealing with the bossy, arrogant father-in-law or the alcoholic stepsister that pukes on your new Persian rug. Sometimes the joy (and stress) of the holidays is in the anticipation of new and out-of-the-ordinary things happening, but most everyone breathes a sigh of relief when they are over as well."

I know that there are some family members I simply cannot deal with, and if they show up, my whole attitude changes. I actually feel badly for my husband, because he usually feels the brunt of that stress. And it's totally not his fault. This isn't uncommon, notes Dr Jory. "Holidays are, by their very nature, stressful," he says. "That’s the idea: Get out of your mundane, everyday routine life and celebrate! Of course, celebrations take planning and effort, and there are often surprises by who shows up, whether they’re on good behavior, and whether there’s good cheer or bad blood." That bad blood can really throw a wrench into a good time.

"The holidays are also a time of reflection and change. We evaluate our lives and consider ways to improve them and this almost always involves reflecting on our closest relationships," says Dr. Jory. "Dwelling on unfulfilled dreams, unexpected character traits, and the realization that your partner isn’t a prince or princess can be a challenge for couples. What we fail to realize is that our partner may carry the same disappointments that we carry."

Terri Orbuch, a relationship expert and sociology professor at Oakland University, told PopScience, “If you feel anxious, rushed, or pressured, your body changes — your heart rate rises and some people say they feel nauseous," which can be a real wet blanket on a party. Even if it isn't long-lasting, that sense of apprehension and nerves can change the way a person behaves.

One word: regression. Joseph Cilona, a licensed clinical psychologist and personal coach based in New York, told The Huffington Post that taking your partner back to their family's house for the holidays might have unexpected results because they grew up there, and now that they're no longer a child, it's a bit like Limbo. “Many find themselves regressing to behaviors, feelings and reactions that they’ve outgrown in their adult lives and relationships but were commonplace during their upbringing," he said.

I might, might totally live in my sweats and eat cookie dough from the freezer during the whole of the holidays at my aunt's house. It's possible. I'm not proud.

Cilona continued, “Although these kinds of responses can occur at any time of the year, the holidays often increase both the likelihood and intensity of these types of emotions and reactions.”

They might not be all that different, but you might not be managing your expectations as well as you thought. Dr. Jory tells Romper that "When we love someone, truly and deeply, we focus on the best in them. We remember that love means taking the good with the bad and that we have our own good and bad qualities. Nobody is perfect — so we have to fight off the idea that we deserve the perfect person in our life."

Barbara Greenberg Ph.D. wrote in Psychology Today that there is a simple reason why your S.O. turns into a different person at holiday gatherings — because they're not as comfortable with those people as they are with you. That can cause them to be nicer, or more introverted, or even more extroverted than they normally would be with you.

After experiencing a traumatic c-section, this mother sought out a doula to support her through her second child’s delivery. Watch as that doula helps this mom reclaim the birth she felt robbed of with her first child, in Episode Three of Romper's Doula Diaries, Season Two, below. Visit Bustle Digital Group's YouTube page for more episodes, launching Mondays in December.