This has been said before. This is a reminder ladies.

Whatever you accept today, you'll accept worse tomorrow.

At first, when he fucks up, it's this massive thing, you're stunned, you cannot tolerate this, you pack your bags, you genuinely plan to leave him. He panics, he starts begging and crying, he's never done anything like this before, he has an explanation for why it happened (he was under a lot of pressure, he was stressed, he was angry, he was lonely). He assures you that it will never happen again (he'll get counselling, he's deleting the apps, he'll go for a meeting). After much thought, you decide to forgive him. You've never seen him so sorry, so broken. You think that after this, knowing how close he came to losing you, that he will value your relationship more. You think that he will treat you better.

Unfortunately, that is not what happens. Of course, in the first couple of days, he's walking on eggshells, trying to show you how sorry he is. He shows you glimpses of the person you fell in love with. But penitence is exhausting, and it will never last. He now knows that when he does this, the heavens will not fall. You will not leave him. The boundaries have been redrawn, and he knows that there are certain things that you will in fact, tolerate.

He will do it again, and worse. This time, however, you will not be shocked, because he has done it before. This time, he might give you a token apology, if he apologises at all.

Again, you forgive him. Then all bets are off. At this point, he no longer cares. He no longer pretends to be sorry. When caught, he attacks you, makes it all your fault.

You stay with him, and change everything you believe about yourself. You revise your entire self-image in the order to convince yourself that this, his treatment of you, is fine. He convinces you, subconsciously, that this is all you deserve. 

By then, he's openly disrespecting you, tearing down your appearance, screaming in your face, openly cheating, beating you, and you have no recourse. You cannot understand what how it got to this point. He used to be so good, so kind. 

We teach others how to treat us. Actions must have consequences. There is no prize for forgiving him, for bending over backwards, trying to save your relationship. Save yourself instead. Get out while you still have your dignity, your self-worth intact. Leave while you can still walk out the door, with your head held high. Do not wait until he has brought you (physically, emotionally, psychologically) to your knees. 

Leave at the first sign of disrespect. It will never get better.