Who hasn't sacrificed to help out their partner? Washing the dishes or getting up to feed the baby when it's her turn to do so. Foregoing the last of the ice cream so that he can have it. They're all little acts of love.

But there are times when such sacrifices might be a bad idea.

Usually sacrificing to help out your partner is good for your relationship — it makes you feel more committed.

But when you've already had a stressful day, even small sacrifices can be a bad idea. What's normally a small favor turns into just one more disagreeable thing that's on your plate.

You'd expect that people on the receiving end of the sacrifices would at least appreciate them. They didn't show it in this study.

The study, by researchers at the University of Arizona, followed 164 couples for seven days. Couples kept an online diary detailing any sacrifices they made for their partner, as well as the daily hassles they experienced. People also recorded their feelings about their relationship quality — how satisfied they were with their relationship, how close they felt to their partner, and how committed they felt to their relationship with their partner.

Most of the time, people who sacrificed for their partner generally reported feeling more committed to them. But on days when they experienced significant hassles, the sacrifice became just one more burden.

Some of the study's other findings strongly suggest that couples need to do more talking with each other.

You'd expect that people on the receiving end of the sacrifices would at least appreciate them. But they didn't show it in this study. It appears they didn't even realize that their partner had done anything special on their behalf if they were already feeling hassled.

The study also found that people's daily hassles strongly reduced partners' feelings of closeness and satisfaction with the relationship. No matter which partner had the tough day, both partners suffered. Many people are poor at compartmentalizing and often take a bad day at work home with them. They come home feeling grumpy and end up making their partner grumpy. If this happens often enough, it can poison a relationship.

Couples need to find a way to work through it. And while there's no single surefire cure for stress, all solutions start with talking things over.

The study is published online ahead of print in the Journal of Personal and Social Relationships.