Oh, this game sounds kinda fun.
Hmm... Well, the marry choice requires little thinking, it's Tessa. By far the most likeable personality and by far the hottest of the three.
The other two are more difficult, mainly because I've only seen one episode of Iroha. I don't have a terribly clear idea of her personality, or how she has developed during the following 15 episodes. I guess I'll go with Chidori for the fail date, because while she doesn't have an altogether bad personality, she's still a bit too tsundere to be healthy in real life.
The remaining choice is Ohana. She's cute enough, cuter than Chidori, and I don't mind a dreamer personality. I'd actually consider her for the marriage choice if not for such a clear winner among the three.