Ino's not dumb so yeah, in time it'll start to eat at her. The thing about the false relationship is that one of them ends up liking the other, but until that time I think there's a smokescreen of lies that Ino's trying to look through. Until one of them starts feeling something real, it'll never really be convincing, and I think once Shikamaru isn't just PRETENDING he'd be more impressive to her.

So, Ino should use this time to realize that Shikamaru is actually capable of being a boyfriend, something she didn't actually give thought to prior to this moment. However, developing feelings shouldn't come until they work together as a unit later on; he's on her radar now, more than before, so Sakura did her job well. 

Shikamaru and Sakura do genuinely get along, and I think she'd just need to convince the one that does not see that at the time. Shikamaru is infatuated with Ino now, but he'd have more fun doing nerd shit with Sakura than doing anything Ino actually likes doing. I see Sakura enjoying clouds, but I don't see Ino enjoying them as much. etc etc.