Well, there's honestly no reason to beat around the bush about the facts here. Especially since it would make her friends happy.

"Well, honestly, I don't really know how much longer this war is going to last ... but don't we spend enough time traveling that she could, I dunno, go with you to the sea?" Here Katniss stopped for a moment.

"In fact, we should get all the Rifters out more. Do you know Ariande doesn't even know what lyrium is?"

She arched an eyebrow at her friend "Thus, my point is made. I don't wish anyone to be stuck far from home -- but if they're here they can make another home with us." She tilted her head slightly, "... Well, if you're not sure yet, then it's not time to talk to her."