1. Small Talk
Research has shown that couples who engage in regular small talk will experience less arguments and fights throughout their relationship. Connective small talk doesn't mean bombarding your partner with an hour-long diatribe about every single thing you did during the day. Small talk is simply sharing opinions or observations from things you did through your day. It also means learning to avoid mono-syllable responses and actually showing a bit of interest in what each other is saying. Ask questions and respond to your partner with positivity.
2. Eye Contact
How many times do you really look your partner in the eye when you talk together? As relationships progress, many people tend to look in the direction of their partner's eyes, but they don't make eye contact. When you first met, eye contact would have been high. Humans react to eye contact as being a positive way to build intimacy. As you become more familiar with each other, this decreases over time, which also leads people to believe the intimacy is dying.
3. Non-sexual Physical Contact
Learning to touch your partner and encouraging them to touch you too in non-sexual ways can help to increase intimacy. Give your partner a hug without expecting it to lead to anything further. Offer your partner a back massage or a foot rub and don't have an ulterior motive. Hold hands when you're out together. These simple forms of physical contact re-establish a level of intimacy and trust in each other that can be very effective in how to fix a failing relationship.
This could be something as simple as going out for a meal or a movie with friends, coffee with the girls, or football with the boys. Research shows that many couples improve their relationships when they display trust and encourage each other to spend a little time doing things they enjoy.