ABANDONED. Fantasy fiction - fictional but inspired by Britons?

[Eli]

Hope someone can help me with the below. Can't remember title or author or any of the main characters' names

I do remember it was fantasy. Starts off with young adults, I think there are four in a group and I recall there was some competition to be considered an adult. A hunt, a chariot race and something else...

At least two of these are born to a Royal family but I think one of them has grown up away from his parents. Think one of them might have been conceived at some fertility/harvest festival and there's doubt about his legitimacy. Definitely rivalry between the two male main characters.

Memorable events. 2 of the main characters, said two are romantically involved and I think one of them is a charioteer and the other a warrior at this point. They help a farm town from raiders from the sea but taking one of the raiders as hostage. Hostage is a female and becomes a strong character in the book.

The two from abov later get separated as she is promised and wedded off.

[Lobstergirl, au gratin]

When did you read it? Series or standalone? Author male or female? Remember the cover?

[Eli]

Don't remember cover or author gender at all. As to when I read it, somewhere between 2007 and 2012. No idea when it would have been written but would guess beginning of noughties. I think, maybe, I came across it reading up on recommendations after reading Scott Lynch's republic of thieves but not sure.

[Lobstergirl, au gratin]

Eli, are you still looking for this or did you find it?

[Lobstergirl, au gratin]

No response. Moving to Abandoned.