In any toxic relationship we strive to resist the abuse with peace-filled, godly response. Knowing fully well we've got our limits! This includes establishing healthy boundaries where you are less vulnerable to abuse and, if God directs, it may mean ending the relationship (easier said than done when the abuser is a parent,a spouse,or a child). The act of forgiveness doesn't require you to stay in an abusive relationship. If you stay, the next thing people will get to read about you will be your obituary and you can explain to God that the reason you didn't fulfill your destiny is because you decided to follow man.... Lol.
But seriously now, you complain that: "she/he does this and that too much, you just can't tolerate the excesses" But have you taken time to question that which you do too much. Relationship is two sided, whereby one has to be considerate about the other well-being; physically, emotionally, mentally and in all areas. It just can't be about you and your needs alone. So, when you feel like pouring your frustration on your partner, remember everyone got stuff they are dealing with.
The first thing one should do is walk away from toxic relationship especially if you are not married and then forgive the person. Forgiveness seems hard right? but forgiveness isn't for the offender its for the abused, somebody said "holding a grudge is letting someone stay in your head rent free."Forgiveness is not the same as agreeing with an abuser behaviour. So seek counsel and talk to God. You know He is the beginning and the end. His promise is,'I will instruct you and teach you the way you should go'. Cheers!