There are lots of lists out there that teach you how to blame the other person for your relationship issues. They suggest that if you eliminate "this type of person", you will be successful in love
Many spiritual philosophies suggest a) you attract what aligns with your vibration and b) the relationship will reflect your unexamined patterns and cherished beliefs. Together you will create a third entity called your relationship.
Here are signs that your unexamined patterns and vibrational differences are playing out.
1. You explain his behavior to others
This is an example of not seeing reality as it is. When you explain his behaviour, it suggests you are not comfortable with what others see and you hope if you convince them,they will share in the story you are projecting over top of who he is.
2. Family and friends try to talk you out of being with him.
Like the previous one, it's possible you are not seeing the whole of reality. Often we are in unhealthy relationships because a need of ours is being met. We may ignore every thing else to protect that need. People who love you take a broader view.
3. You are unhappy a lot but believe YOU will change and do better.
A twisted version of consciousness practice can include deciding "well if this relationship is bad, then I better change since I am the root of this". To some extent, that is true. But not true enough to take on all the blame and all the responsibility for the thing you both created - the relationship. It's possible you must change to align with your happiness. It's also possible you no longer vibrate together, are drawn together. So ending may be the answer.
4. You leave and come back. Again.
When you make the decision to end a relationship, there is a reason. When you come and go, it also suggests that part of you sees the whole reality, but the need being met is more important than the relationship itself.
5. The moments of incredibleness are far less than the moments it's an incredible mess.
Relationships have ups and downs. That is how we grow. When we grow together, there is a happiness - like being apart then returning. We may disagree or be challenged for a bit. But as we grow, we often grow together - particularly if we value the third entity - our relationship. We move together towards something bigger.
When it's unhealthy, we grow like scar tissue. We protect that one spot where our needs are met, even if it means limping and over compensating every where else. Eventually, like an untreated injury, we are almost always in pain.
If these things resonate, they are pointers towards where we have spackled over our true nature with illusions and false beliefs. It may be beliefs caused by abuse, by trauma, or by repeated views by those around us. Regardless, they are direct pointers to the longing of our deeper nature wanting to be expressed.
In a healthy relationship, you will do the work together. In a relationship that is over, as you change, there will be more discord and friction.
But friction polishes diamonds.