Base your relationship on friendship
There’s a mutual respect that comes with a friendship that is essential for a successful relationship with anyone – partner or not. Building your relationship on the basis of a friendship can help you learn about them without the added intensity of a relationship. For example, talk about everything, literally. If you’re watching the news together and a controversial story comes up, talk about it! You’ll learn a lot about each other’s moral compass and whether you are compatible as a couple or not.
This sounds obvious but is a surprisingly common pitfall. If you have any respect for your partner and the sanctity of your relationship then don’t play away. Even if your partner can bring themselves to forgive you, they will never forget. It will ultimately eat away at your relationship and the trust will have gone.