Because Love is Sacred
Love is the feeling which contains not only happy moments but also hardships, difficult decisions which one must make in order to save the relationship from crashing at especially critical points.
Love is a wonderful thing, true love is sacred, and if you feel that you have found your true love, the love you can live without but this 'life without' would be just too gloomy and senseless, it's more than worth fighting for, sacrificing for, contributing your everything to it.
True love gives you wings and helps you learn to fly, that's why if you really love someone it won't be too difficult for you to sacrifice even the most important things to be able to cherish your romantic union and carry it through eternity of your life together.
True love is hard to find, that's why it's important that you do your best not to lose it, otherwise, it may maim your life in the long run. However, it's also very important to be wise and sensible enough to be able to appreciate the situation – whether your sacrifice will be appreciated or if it will manage to save your love or turn it into eternal flame of passion, beautiful garden of respect, vast ocean of trust and bouquets of amazing moments spent together. It means that it's very important to realize or at least to be warned by someone close and sensible that your love is blind and your sacrifices are all in vain – in case the situation is really and truly so uninspiring.