You must avoid the temptation to argue with your lover, no matter how convinced you are that you are right and your partner is wrong. Instead, make a great effort to allow each other the right to your own opinions.
There are many ways to do this and still maintain a functional relationship. One way is to divide the responsibilities, so that you each know who is responsible for what. This approach will clarify the facts at issue, so that they are not subject to debate. You'll find that your affair will go much more smoothly.
In time you will overcome the temptation to argue. Most important, you will have an increasingly clear perspective on reality and more effective control over your ideas.
Experience will teach you to use demonstrable reality as your most effective argument, which will eliminate the need for wasted words and emotions and will enhance your partner's respect for you.