When Rin can't find Haru after their first meeting in an oasis, where he spontaneously proposed, he restricts water to the nearby land, requiring anyone who needs water to apply for it, in a bid to see Haru again.
The art in this is GORGEOUS. Although others called this dubcon, I didn't get the sense that was the case. Haru didn't resist a physical relationship with Rin - he resisted becoming his property. I think Rin was hoping that by having sex, Haru would change his mind and want to stay with him. Haru's twist is to suggest Rin become his instead, and it ends on that note (and Nagisa revealing he knew what was going on the entire time).