Prince Harry and Chelsy Davy tried to make their relationship work before they eventually parted ways.

Prince Harry and Davy dated on-and-off for years. In fact, she's his longest relationship to date. According to Katie Nicholl, the two attempted to save their romance, but to no avail.

"You sort of get the feeling that neither of them were quite ever willing to completely let go of that love affair. They'd carved their names into one of the tree trunks on the family estate. It was such a love affair, it really was," Nicholl told InStyle.

"Right up until 2015 they were trying to give it another chance. I was quite struck by that and I think everyone that's been in love, you know, you never forget your first love, and in that respect, I think Prince Harry was no different," the author of "Harry: Life, Loss, and Love" added.

Prince Harry and Davy reportedly went to Africa in 2015, years after they broke up. Several sources told Nicholl that "both hoped there might be a chance of a reconciliation." They apparently spent time together that summer, but they didn't rekindle their romance.

According to Nicholl, Prince Harry and Davy's relationship did not work because she didn't want the life of a royal. However, they still managed to maintain their friendship.

Nicholl noted that "there's that amazing respect between the two of them." She added that neither of the two spoke ill of the other in interviews.

"Neither of them have spoken about their relationship and I think you have to respect and admire them for that," Prince Harry's biographer said.

In related news, journalist Richard Eden recently claimed that Prince Harry is inviting two of his exes, Davy and Cressida Bonas, to his royal wedding with Meghan Markle.

"Harry has stayed good friends with Chelsy and Cressida, so they will be there, one of his pals tells me," Eden wrote. "He made sure there were no hard feelings when they split up. I don't think Meghan will mind."

However, another source said that Davy might score an invite, but not Bonas. "Both [Prince Harry and Markle] will be going through the list carefully. Don't expect to see Cressida invited —the two didn't remain friends— but do not be surprised if Chelsy shows up with a date. The two have remained friends long after ending their relationship and still keep in touch to this day," an insider told Us Weekly. "Meghan would have no problem with her being there and Chelsy was on the preliminary list of friends to invite."