The first thing that you should learn is not to be critical of others faults, particularly the faults of someone who could become your partner in life. No one wants their faults to be pointed out. It is basic courtesy that you should not be too ready to find fault with your partner.
It also happens that people who are anxious to find a partner are quick to take up a relationship with someone who more or less is the sort of person they would like to live with. In their haste to build up the relationship such persons ignore obvious differences and fail to realize that the relationship may not work out in the long run.
Persons who are very eager to establish an intimate relationship with someone they think is suitable for them, tend to erase their own personalities so that they can fit in better with their lover. The obliteration of personal beliefs and character will not help strengthen a relationship. One should be truly honest with oneself.
Fear is a major factor which blinds a person from seeing that a breakup in the relationship is looming. People fear being left alone without a partner; they fear that they may not be able to fend for themselves; and they fear that they will not find anyone else to love them and share their life with them. This sort of fear will make the relationship very difficult and painful to endure. While fear is something that we should take seriously, we should not allow it to overcome us. This is what Dr. Susan Jeffers talks about in her popular book called, "Feel The Fear And Do It Away"
In our attempts to get rid of our fears about loneliness we tend to ignore instances that are not pleasant and find excuses to absolve the bad and hurtful behavior of our partner. We do this so that we could keep the relationship going.
It also happens that very often we find it difficult to own up to our errors and faults. We feel too proud to say that we are sorry. We might also find that it is humiliating to accept that we were in the wrong.
We tend to focus on all the good things, real or imagined, in the relationship and turn a blind eye to what is not right with it. We just want to feel happy about it and refuse to look at anything that is not right about it. Then, when the breakup eventually happens, we wonder how we could have been blind to everything that was wrong about it.