Two male long-jawed orb weavers, Metellina segmentata, square up over a female. The male on the right was in the web having already mated with the female having presented that wrapped up fly as a gift to distract her, while the male on the left has just arrived, bearing a gift of a paltry greenfly.
At first the female stood in the way, but she soon backed off and left them to fight each other (even though she could probably kill them both if she wanted to). The fight was over in a few seconds as the rival realised he didn't stand much chance, and left with his life and legs in tact. After the second male departed, the female returned as canoodling with the original male continued over dinner.