It is one thing to stay on polite terms with an ex.

It is an entirely different ballgame to invite your ex to your wedding.

Take Valerie Bertinelli, for example.

Princess Catherine and Prince William’s wedding day kiss

Former power couple Demi Moore and Bruce Willis attended each other’s weddings to other people.

(We wish we could all say the same.)

While Charles might have loved having Camilla at the ceremony, Diana decidedly did not.

King Charles III and Queen Camilla

To this day you know vivid memory," the princess recalled.

Still, it was kind of strange to see him there.

So the affair went on until Charles married Diana, and then picked up again in 1986.

Queen Camilla with Andrew Parker Bowles

William even spent one summer vacation with Craig in Kenya, despite Catherine’s reservations.

This was when King Charles III decided to step in and give his son a much-needed talking-to.

Hunt and William dated for a while before Princess Catherine dazzled William at a St. Andrews fashion show.

Split of Prince William and Jecca Craig

Catherine famously showed off a sheer dress on the catwalk, and apparently, that was that for Wills.

Those who keep tabs on royal exes will know that Hunt moved on with Nicholas Wilkinson.

William dated Musgrave in 2001, and the relationship lasted for about a year.

Split of Prince William and Olivia Hunt

After they met at a party, they started what Nicholl calls a “passionate romance.”

It didn’t last long, and now Musgrave is happily married as well.

William’s relationship with Farquhar was quite different.

Split of Isabella Calthorpe and Prince William

Nicholl described William’s relationship with Farquhar as an “innocent, tender romance.”

Farquhar returned the favor when she got married 11 years later.

All’s well that ends well.

Split of Arabella Musgrave and Rose Farquhar

Before she started dating William, Catherine was in a relationship with Rupert Finch.

He wasn’t terribly sure if she was interested," the source revealed.

As we now know, William eventually stole Catherine’s heart, and she and Finch parted ways.

Split of Princess Catherine and Rupert Finch

They remained friends, however, and as a result, he scored an invitation to her wedding.

He returned the favor when he tied the knot with Lady Natasha Rufus in 2013.

Recently, more details about their relationship were revealed, more specifically about why it ended.

Prince Harry and Chelsy Davy laughing

We’re glad they stayed friends, though.

Their relationship began to fizzle after he returned from Afghanistan.

Harry and Bonas clearly had a strong bond, but they ultimately decided they worked better as friends.

Cressida Bonas and Prince Harry

Believe it or not, Kingston’s ex is none other than Princess Catherine’s sister, Pippa Middleton.

The royal world is a small one, indeed.

It makes sense, then, that he returned the favor when he finally tied the knot.

Pippa Middleton and Thomas Kingston laughing