His story seems shaky, and she doesn't entirely believe he's telling the truth. Even though honesty is a must when it comes to love and romance, trust doesn't happen overnight. Whether the woman suspects that he's cheating or that he's lying about something else, proving his honesty can sometimes help the relationship get back on track.

Help Out With the Analysis

Analyzing the believability of what someone is saying can help set the truth apart from a lie, according to professor of leadership and organizational psychology Ronald E. Riggio in his article "5 Reasons You Can't Tell When You Are Being Lied To" on the "Psychology Today" website. When a man wants to prove his truth-telling, he can help his girlfriend to analyze his story. For example, you tell your girl that you're going out with your best guy buds on Friday night. Saturday she calls you and insists that you lied, and were out on a secret date with another woman. Go back and recount the actions that prove your honesty, such as the fact that you called her while you were out with your friends, or go through the evening's events.

Time After Time

If you catch him in a lie -- or a few -- trusting him in the future won't come easily, according to the article "Am I in a Healthy Relationship?" on the TeensHealth website. When your guy wants to prove that he's telling the truth, the more often he is honest, the better. For example, if he told you that he was going out with the boys on Tuesday, but your friends saw him with a girl, you're not likely to believe him when he says he's spending Saturday with his buds. On the other hand, if he's always honest with you, trusting him to tell the truth isn't an issue.

Her Issues

When a woman has trust issues, it makes proving you're being completely honest a challenge for any man. She may make unfounded accusations or suspect you of lying even when you're being completely truthful. If this is the case, you need to help her to work through her problems trusting men before she will ever believe what you're telling her. This won't happen immediately. Trust takes plenty of time to build. You may need to point out how honest and reliable you are, helping her to know that she can trust you. For example, if she gets anxious when your friend Jane texts you, have her meet Jane to see that the relation ship is completely platonic.

Open Up

Starting your relationship off in an open and honest way sets the stage for your girl to trust in your truthfulness. The more open you are with a woman, the more likely it is that she'll believe whatever you are telling her. This doesn't just mean that you don't lie. Instead, make a point of truly opening your inner self up to her and showing her who you are as a person. Share your greatest hopes, dreams and even fears with her. Doing so proves that you trust her enough to tell her the truth about everything. For example, you told everyone else -- other than your girlfriend -- that you broke your foot skateboarding, which isn't exactly true. The truth is that you broke your foot tripping over your untied shoelace on your way to the skate park. Telling your girl the embarrassing truth shows her that you're open and honest with her.