Life is Mystery

Ok, me too, i can never understand about love too. I think people marry because they are destined to be together, and it doesn't matter whether they love each other and I beleive that love can be develpoed and nurtured. My current mystery, how can people be so thick face, don't know how to be thankful and appreciated what other people do, instead, makes faces to the person that have help, and never concern about other thing, accept her own ego. Well, how can that person not to be thankful?