This 90-year-old former U.S. senator is teaching the world what love is.

If there is one thing that you can be certain about when it comes to love. It’s that nothing is certain when it comes to love.

Not many people are okay with this. When you find yourself in love with a person who, in some way – maybe it’s age, gender, background, race, religion – is ‘unexpected’ to those around you (maybe your feelings are even unexpected to yourself) some tough questions can be thrown your way.

“Sooo, do you only like girls now?”

“What happens if you break up, now you’ve ‘come out’ and all”

“You know you want be able to get married in our church?”

“How will you tell the family?”

With these thoughts in mind, I can only imagine the questions former U.S. senator Harris Wofford has faced over the last 15 years, since the start of his relationship with Matthew Charlton, a man 50 years his junior.

Particularly considering Wofford was married and in love with his wife Clare for 48 years, before she died from leukaemia in 1996.

In an attempt to answer these questions (and teach a few people a thing or two along the way) Wofford has written a moving, heart-felt and very honest column in the New York Times. He called it Finding love again, this time with a man.

“We were decades apart in age with far different professional interests, yet we clicked,” Wofford wrote about his meeting Charlton. “We both felt the immediate spark and, as time went on, we realised our bond had grown into love. Other than with Clare, I had never felt love blossom this way before.”

Harris Wofford and Matthew Charlton. Image via Civic Documentaries.

The essay is one man's journey and not a political statement. But Wofford's story is unique and also makes a potent comment on the way society so often categorises relationships, love and people into boxes that have nothing to do with reality.

"Too often, our society seeks to label people by pinning them on the wall – straight, gay or in between," Wofford wrote. "I don't categorise myself based on the gender of those I love. I had a half-century of marriage with a wonderful woman, and now am lucky for a second time to have found happiness."

Wofford brings it back to the very thing that should be at the heart of any relationship – love, devotion and feeling. He also revealed his plans to marry Charlton this weekend, on April 30.

"To some, our bond is entirely natural, to others it comes as a strange surprise, but most soon see the strength of our feelings and our devotion to each other. We have now been together for 15 years."

"On April 30, at ages 90 and 40, we will join hands, vowing to be bound together: to have and to hold, for better for worse, for richer for poorer, in sickness and in health, to love and to cherish, until death do us part."

Ups to you Senator. For breaking through those 'boxes', pouring your heart out and, most importantly, for not letting the opinions, doubts and questions of others (I'm sure there were more than a few) deter you from following, owning and celebrating your happiness.

It's time for marriage equality in Australia.