Sacrifice = Love ???

A friend of mine questioned about the importance given to the act of sacrifice towards the manifestation of love.
Is Sacrifice a measure of love? Greater the sacrifice, deeper is the person's love?
His question is not baseless. He quoted many popular love stories in history , "Romeo and Juliet" , "Laila Majnu" have tragic endings.

Normally I ready myself to contradict his statements for the sake of argument. But for once, I was not able to quote a powerful love story that did not involve sacrifice.
Agreed that my knowledge is limited on this subject, but the very fact that I knew about many tragic love stories & not one with a happy ending was in fact troubling me.

Is it how our human brain is built, increasing the longevity of painful memories when compared to happy thoughts?
Is it because we have raised the bar for happiness?
We no longer recognize simple pleasures like reading a good book, enjoying a fine meal as happiness. We expect happiness to storm in and sweep us of our feet.

I still can't shake his question...What is it with Sacrifice & Love?

I can understand "Passion & Love" ,even "immaturity , inexperience and Love", but sacrifice & love looks like a paradox, but literature seems to glorify it.

This topic was a bit touchy to argue about as it was close to my friend's heart. :)
My friend is lucky in love and he is a happier person. It should be THAT simple. You fall in love because you are happier that way.

Some say that there is also enjoyable pain ( seriously??).
They say longing in love is painful, but they enjoy the pain as they know or they believe in its fullfilment.
In that case, I say pain is bearable not enjoyable. People seem to confuse emotions.

No one happily sacrifices, not even for love. It will result in pain.
For me , pain is unwanted and undesirable feeling. The mere mentioning of the word "pain" so many times in this passage will make some readers squirm.

If someone says he has sacrificed for his love and is happy, he is a liar of the worst kind. He lies to himself !!!

Love is to enjoy, not to endure. You don't enjoy sacrifice, you endure it.
Love is to live,  not to exist. You don't live in pain, you exist with it.

Sacrifice = Pain ≠ Love.

Hence proved.

Have I? :)