Love is critical to human experience and existence. It affects our health and emotional states. A great love helps us soar, while the lack of it can crush our capacity for greatness. I am not sure what we are without love, but it isn't pretty.
The famous writer, C.S. Lewis, wrote about love in his book The Four Loves. He described storge as love enacted via empathy, like the love of parent for a child. Philia is the bond of friendship, the least natural of the loves, because it isn't necessary for survival (or so he thought). Eros is the erotic bond between lovers, the experience of falling or being 'in love' with another. Finally, agape is love that serves others regardless of circumstance, selfless love.
If you engage 3 of the 4 loves - storge, philia and eros (empathy, friendship and erotic) - with your significant other/partner/spouse, you will end up expressing the 4th love, agape. In any relationship (not just sexual or romantic), deep embodiment of empathy or friendship will lead to unconditional acts of caring.
I completely disagree with Lewis's take (a religious view) that you have to subordinate the other 3 loves to experience or give unconditional love (which was reserved for the love of god, or a god-like love).
We are the Gods. If we don't exhibit and practice unconditional love, who will?
Love that is given when it's inconvenient, time shared when you think you have none, empathy given when another is in deep need or a dark place - this is the love that is so human. This is the love of the 'Gods' that we are perfectly capable of. Natural loves LEAD you there. Eros is a most powerful force that will cause you to do or give anything to your partner, regardless of pleasure to the self. Philia bonds can become so deep that unconditional moments erupt naturally - like the love of a brother for his sister. And storge...well, the selflessness of a parent in deep love with their child is a beautiful example.
So love fiercely. Do not allow weak excuses, the disease of busyness or perceptions about who deserves love to cloud your acts. Love is energizing, it won't let you down.