The fault you see in that person may be the reason why God put you together in that relationship. Instead of complaining about his incessant misbehaviours, ask God to show you how He will use you to help him in that area. Your persistent forgiveness may even be used as an instrument in God’s hands to help this individual overcome his weakness.
“If he sins against you seven times in a day, and seven times comes back to you and says, ‘I repent’, forgive him”. (Luke 17:4 NIV)
Offence and forgiveness go hand-in-hand in any relationship that will last. Keep forgiving, there is no limit to forgiveness.