Cheating is one of the biggest tests a relationship can face. It's not easy to build back trust the lost after someone is unfaithful, but some people do manage it.
Matthew Hussey told Business Insider: "Cheating is a fundamental relationship-altering event and it's a huge breach of trust on a deep level.
"Even if you can overcome what happened, it plants this seed that then grows."
For someone who never even considered the possibility of their partner cheating before, it can become a constant possibility in their head, he added.
"Whatever justifications you give for your actions — that you were feeling insecure or going through a bad time — you've shown me your reflex response to those emotions and now I'm terrified that any time you feel like that again, this is your logical end point," he said.
Firstly, know it's a long healing process
But the good news is, Hussey does believe that damaged trust can be earned back, but through what he terms as a "process," which is by no means instantaneous.
"It's something that you build, there's no getting around it. It's a long, slow process of good decisions and actions everyday that build that wall again. There are no short cuts," he said. "Anyone looking for that quick fix pill... is not living in the real world."
He added: "It can happen, you can get back to a place of trust and I truly believe you can get stronger after cheating, but it will take time and you have to care about that person and the relationship enough to get through the process."
Next, establish the "root cause"
According to Hussey, communication is key. The perpetrator must ask themselves why the infidelity happened and then communicate this to their partner, to assure them that it won't happen again.
"Things that will help [the process] are communicating to that person that this is something that won't happen again, and in order to do so, you need to tell them why it happened.
"The why part of the process is something lots of people don't do, but people need to explore why it happened in the first place. Were you weak, selfish, insecure or looking for attention? Understanding the root cause is really important."
He went on: "You're not just going to say this won't happen again, you need to explain why. Because you resolved your issues or insecurities or found a better way to manage them? So that you come from a place of credibility rather than blindly saying sorry, it's not enough. You need clarity.
Hussey believes that a lot of hurt felt by the cheated on partner can be alleviated by helping them to understand what's going on in your head.
Be proactively honest
What Hussey likes to call "proactive honesty" is also crucial to this process. This, he explains is when you offer up additional information and details first, rather than simply answering questions, or "reactive honesty."
"For example, if you went out last night, give more details than you normally would on who you hung out with, what they would have 'loved,' that you were talking about them, etc."
Going out of your way to make them feel secure and comfortable will help put them at ease.
Finally, make a trust pact
Finally, Hussey said that if you're really committed to building back the relationship after someone has cheated, it's absolutely essential that you do one thing: Make a pact.
"The pact is this: I know what I have to do to keep you, I know I have something to prove to you and rebuild, but I also need you to do the hardest thing in the world and give me your trust again.
"You've got to be able to hit the rest button and start again."