The last thing a lot of people want to do is serve others. It's a commitment, it's time consuming, and sometimes, you feel like as a struggling couple, the worst thing is to have to spend time together, sacrificing your time for other people. However, serving together, even for one hour a week, can be hugely beneficial for your marriage.
The definition of stewardship is "the activity or job of protecting or being responsible for something." To God, this means our financial resources and our time. While tithing is important, serving together is also what God calls us to do. Serving someone or something else (like a ministry) allows you to see your spouse in a different light than maybe how you've seen them. It also allows you to work together for a common goal.
One of the biggest reasons people don't serve is because they don't think they are good enough, it's a commitment of time they don't have, or they don't think they know enough about the Bible to actually be a leader. Serving allows you to see that all of these things get worked out by God if you are doing what He is calling you to do. You'd be surprised at how much your schedule opens up and how much you can enjoy your time together while focusing on something else besides your own marriage for a change. I highly encourage everyone to find a place where they can serve together, even if it's not in the church.