Part of any emotional bond is the thought of losing it, and this is often the basis for jealousy. A person experiencing it could have their own set of trust issues from past relationships with parents or a spouse, but it might also be related to their lack of confidence. It matters little what causes the problem if the couple is not willing to do something about it, so solving trust issues should always be a priority whenever a couple begins experiencing them.
Honesty is an important part of any relationship, and those unwilling to tell their partner what is bothering them could find their problems escalating. If they do not trust the other person for any reason, getting it out into the open could go a long way toward solving it. Their partner might be the type of person to leave out details when speaking, and this alone could be creating a bad feeling in their partner. Talking about it will give both of them an opportunity to attempt a solution.
Professional assistance is often needed when it comes to solving trust issues between people in a long term relationship, and it has become less of a stigma than it was in the past. While few people really want to go to counseling, it could be the only path that will save their future relationship. Those who are willing to do it with an open mind and heart could find their problems are easy to solve with a few minor changes in how they interact with their partner.
Not all trust issues will have a solution in a relationship, and there are times when a jealous person finds they have a good reason for their feelings. Pushing their partner to help them find a way to fix the problem could lead their partner to admit an affair or a lack of interest in being with their spouse.