When you are in a loving, compatible relationship it is great. Love is amazing when you are so deeply in love and have that someone special to share your life experiences with. There are a lot of people out there however who are in a very unhealthy relationship. There are a few situations in which it would be considered as an unhealthy relationship.
It does not matter the specific details, any relationship that has mental or physical abuse is not healthy and it is really just as simple as that. No matter how long you have been with that person or how much you think you love them, if they are being physically or mentally abusive with you then you cannot just sit by idly. In most cases men are the abusers but the rate of female abusers has increased significantly over the past few years. In other situations, the abuser can get help and the couple may be able to work through it but the first step is to get away.
The only way to help an abuser is to get away from them immediately. Most people who abuse others were abused themselves. This is normal but using violence as the answer or degrading someone to make you feel better about yourself, this never is. No woman or man should ever feel obligated to stay in an abusive relationship just because they love that person.
This unhealthy behavior is just going to continue unless you take that step and force them to get the help they need. Hopefully there are no children involved, and you are both going to need therapy and deal with your issues before even considering getting back together or with anyone else for that matter. Another example of an unhealthy relationship is when one or both parties are abusing drugs or alcohol. Especially if this problem started even before you got in the relationship, the biggest problem is that you probably do not even know each his or her true personality.
You may want to consider, if you are in a relationship with someone who was on drugs or alcohol the first time you met them, as though whether or not you would enjoy being with them when they are sober. You want to be in a relationship that is affectionate and comforting not one that is hurting you. It is not a good idea for either of the parties involved. There are ways to deal with an unhealthy relationship and the worst thing that you can do is just sit by and not do anything about it.