First of all, love is not rare. What is rare is unconditional love. Unconditional love is demonstrated just by the giving of yourself to another without conditions. Spending time with those who only love you when the conditions are right for them will lead to bitterness and will always set up the perfect UNhappy ending.
Unconditional love means to accept someone without conditions, to feel someone in every heartbeat, to find someone in every thought, to see someone with eyes closed and to miss someone without reason; just because! To love unconditionally means you don't need the other person to be different than they are in order for you to be happy. They make you happy by just being themselves.
Close your eyes and think of your child or grandchild reaching out for your hand in total trust. Think of those puppy hugs and kisses that only a puppy can give without conditions being met. Watch a child and their pet interact and that picture should be in the dictionary beside the word and definition of unconditional love.
The concept of unconditional love is not always an easy one to understand. You are not going to promise to each other that there will not be disappointments because there will be at some point. The fact that you don't run away and leave someone because they disappointed you is the unconditional part. It is okay.
This kind of love is a state of being. It is a love for no reason because there are no demands, no fear, no rewards. It is basically a universal language that all can understand with an open mind. You give it without expecting anything back. When two people meet that grasp this concept, they begin to see that they may not be expecting anything back, however, they get volumes of love back.
To me, it should be part of the official marriage vows. When the judge or minister or priest states do you take this person to be your husband/wife and do you promise to be faithful in good times and in bad, in sickness and in health and to love and honor all the days of your life? How about adding and I promise to love you unconditionally. It is a choice. You either will or you won't. It is keeping someone in your heart regardless of other conditions.
One very important part of unconditional love is knowing that it does not stand for accepting bad behaviors. Behaviors that are illegal most definitely would be a deal breaker. (Unless you just want to go to jail with your partner - separated, of course).
Find a heart that will love you at your worst and arms that will hold you at your weakest.