Jealousy?

They had arrived in the town of 'Alabasta' and the people there welcomed them and celebrated their welcome.
You had been drinking with Marco, competing for money, but you didn't win, so you started exploring the place, but in the distance you saw Ace surrounded by girls.
Ace was lying down with his head in a woman's lap, smiling quite contentedly.
"This is paradise..."
Ace murmured, burying his head in the woman's lap, and for some reason, you felt a discomfort...
You were used to seeing women/girls flirt with Ace, but this time you didn't like seeing that.

You saw him but decided to leave. Later, you ran into a guy named Axel. You talked for a while until night fell. He suggested you make a bonfire, which seemed like a romantic date.

Ace was still asleep in the girl's lap when he remembered you. He left the women there and went to find you. When he saw you with that boy, a pang of jealousy shot through him, and he decided to stay hidden, watching you.