Oh Aria, Aria...
I get that you're happy, but you shouldn't be abusing this hourglass too much. Tactical moves are fair, but if this hourglass really drains your lifeforce or has some other unspoken cost, you should keep the pranks to a minimum.
Oscar...sounds like he's be a serious, stand-up fellow, so this response from him is fair. It's pretty villainous, but at least Aria isn't actually interested in seducing him so much as getting Mielle jealous.
I'm sure she can spin this as a rendezvous with him that'll drive her sister mad. Ooo...I wonder if she can provoke Mielle to behave so erratically it puts Oscar off?