what i feel is that love, trust and understanding go simultaneously.If a relation has love and does not have trust and understanding, it may not work.You may love someone yet you may not understand his/her feelings and may not trust his/her acts.A relation with love and understanding again cannot work.You may say that i love you and understand why you did something but i'm sorry i still don't trust you.And a relation with love and trust too cannot work.You need to understand each other properly.
Now the question arises, "what if some relation has only understanding and only trust?"Then all of us on thinking a little will realise that such relations work very well in the professional life.A relation of a boss with his employee works on the understanding factor.They understand each other's views.And similarly colleagues trust each other and a leader trusts his teammates that yes,"I trust them and i am sure the work will be done."
But to bring human beings together into a relationship that lasts long and is smooth, all the three factors are important-love, trust and understanding.With these three, there will be no doubts and no suspecting, and the individuality will be respected.
A very common day to day experience can be quoted. Imagine your friend is not talking to you and she is really sad and after your constant trying she is still not saying anything.In such a situation if the relation has love, trust and understanding, you will then stop asking her. You understand that she is sad, and needs time alone.Your constant asking will only irritate her. You trust her and you know that she will tell it to you someday when she'll be fine.And you love her, that is why , despite her not telling the thing to you , you support her to make her feel better.In this way you have respected her individuality and you have given her love, trust and understanding.
So all humans come together, yet respect each other's individuality with love, trust and understanding!