There's no avoiding that fact that mistakes are made in every relationship. Even the ones that seem the most perfect. In fact, overcoming these mistakes is often what makes certain relationships grow stronger. One thing you need for this to happen is openness and honesty. As soon as you start lying to your partner, it's a slippery slope towards your break up.
A man who is truly in love with you will never lie to you. He loves and respects you so much that he religiously sticks to 'honesty is the best policy'. When you're honest about what you're doing, there's no nasty surprises and nobody ends up feeling betrayed. If your partner is going out for drinks with a female friend, he'll always be upfront about it. This honesty means you'll never feel threatened or insecure.