Spoiler (mouse over to view)
I mean, everyone else gives up and accepts fairly quickly that their loved ones are dead, but those two still hold out despite all evidence the rest of humanity is dead. Of course, as it turns out they are actually both alive and were sent to the future due to Hana's father. But still...they had no way of knowing that.
I've found I liked both their characters a lot more when they stopped the continuous pining for one another every five seconds. (other than that, I reeeeeaaaaally love this manga! haha)