"In my practice I notice that many couples feel stressed about the frequency of sex," Miller says. "This disagreement can also affect the amount of affectionate touching because the partner who wants less sex may 'freeze up' if they think an affectionate touch is an invitation." It's not uncommon for the amount of sex to slow down once you get into a more comfortable place in your relationship. According to Miller, one way to resolve this is to schedule sex. That way both partners are prepared. "The in-between days can be designated as 'no sex' touching days," she says. On these days, you can focus on building intimacy and connection through other ways like having meaningful conversations in bed.

"This one is inevitable," Deanna Fernandez, MHC, NYC-based psychotherapist, tells Bustle. It's hard enough to deal with your partner's family when you don't get along. But when you're really cool with them, it can still be tough to figure out who you're going to spend holidays with or how to set proper boundaries without anyone's feelings getting hurt. According to Fernandez, this can be really stressful for any couple. The best way to deal with family issues is to talk to your partner and approach it as a team. "Couples counseling can also help offer insight to any problems and help each partner identify better ways to respond to particularly difficult family members," Fernandez says.

Major life changes like moving, starting a new job, or losing a loved one can cause a ton of stress. "For long-term couples it can be extremely challenging to be thrown off your normal routine," Fernandez says. Sometimes these things happen suddenly, so you can't always be prepared. If your partner is facing a transition, find a way to be supportive. As Fernandez says, "The transition will inevitably impact you, so check in with yourself about how it’s affecting you and what you may need from your partner as well." It's also important to keep the lines of communication open at all times.

Money issues can cause problems for any couple, and even happy couples aren't always immune to it. Being a saver while your partner is a spender can cause some arguments between the two of you. But according to Celia Schweyer, dating and relationship expert from DatingScout, it can be even harder when one person makes more money than the other. When there's an obvious imbalance, it can cause resentment to build if your issues aren't being aired out as they come.

"The partner who earns more may not really mean their reproaches, as it could be driven by stress from work," Schweyer says. "But when words regarding money and work are laid out in the open, serious damage [can] follow." To avoid things blowing up during a heated moment, the best thing to do is to keep talking about your finances. When everything is always out in the open, there's no room for surprises.

As fun as going away with your partner can be, it can also be really stressful. More often than not, couples start seeing tension during the planning process. "This is actually a common thing I hear in couples therapy," Christine Scott-Hudson, licensed psychotherapist and owner of Create Your Life Studio, tells Bustle. "Couples have widely differing ideas of the 'perfect vacation.'" Your idea of a perfect vacation might be getting up at noon and relaxing by the pool. But if your partner wants to get up early and see as much of the area as possible, it may not be the bonding experience you hoped for. Planning a vacation together can also bring up issues in how you choose to spend and save money. Communication and compromise are really important here. "Talk about what you would like without making the other one wrong," Scott-Hudson says. "Respect your differences."

As silly as it may seem, research has found that arguing over household chores can lead to divorce. "Someone will always feel like they’re doing more things in the house, especially when you don’t have clear task divisions," Schweyer says. The best thing to do in this situation is to simply assign chores. You can even keep a schedule of your tasks for one day and then rotate. When both of you agree on the list, you'll argue less and have more time to be loving and affectionate with each other.

When you first get together, you may agree on on your plans to move in together, get engaged, get married, and then have kids. If you're really lucky, your life together will go exactly as planned. But for the majority of people, it doesn't always work that way. The goals you made as a couple when you first got together at 22, won't be the same as the goals you have at 30. "When your goal seems to be going in the opposite direction from your partner's, it could be a problem," Schweyer says. This doesn't have to mean that you're meant to break up. But it does mean that you'll have to have a discussion about where you see yourself in the next five to 10 years, and whether your partner feels the same. "When you both want different things to happen, the only way to go is finding a middle ground and compromise," Schweyer says.

It's easy to see other happy couples and think they've got everything figured out. But that may not be the case. The reality is, nobody really knows what's going on in a relationship but the people in it. There are a lot of things couples do behind closed doors. These are just some of the stressful situations long-term couples go through.