Building trust in a relationship can be very difficult depending on the circumstances. If one partner had an affair, then it may take several years to build trust in a relationship. It can be done and marriages survive affairs but it will take time. The person who had the affair will need to apologise to his/her partner and then be prepared for that person to learn to trust them again.
But trust is something that needs to be built up in every partnership. After all you are going to share your life with this other person so you need to know that they share the same values as you do. If you are trying to build mutual reliance there are several ways of doing this:
1) Make sure your words and actions match. If you say you are going to be home at a certain time, then make sure you are or else phone in advance to explain why. It is the little gestures that define who we are.
2) Always tell the truth no matter how painful. Lies destroy every type of relationship from friendships through to marriage. Telling the truth isn't always the easy option but it is the safest. If your partner knows that you always tell the truth, they will trust you much quicker. If they hear you telling lies to others, even those that you dismiss as being small or white lies, they will have less belief in you.
3) Do not keep secrets when in a relationship. Now I don't mean that you have to tell your new boyfriend or girlfriend your deepest secrets but as soon as the relationship looks like it is becoming serious, it is a good time to make sure that any relevant history is out in the open.
4) You need to have faith in your partner before expecting them to return that trust. If you have to text them morning and night wondering where they are and who they are with, they are likely to think you have something to hide.
5) Don't be unrealistic. All relationships have issues even those that have been happily married for 50 years. You need to accept that being part of a couple means that you take the good times and the bad. If you bolt at the first sign of trouble, your partner is never likely to trust you.
6) Finally rely on yourself to do the right thing. You must first know yourself and trust in your ability to make the right choices before you can trust anyone else. You have to know what your own goals and aspirations are in life before you can share a meaningful existence with someone else. Somebody with a defined sense of values is more likely to trust another person, as they will quickly recognise these similar values.
All good relationships are built on a number of factors so learn how to build trust in a relationship now to increase your chance of success.