Define what "enough" time is? I would still search for them even after 5 years probably after 10 years. There is always a chance they are still alive.
It's very hard... even regular circumstances in which people pass away swiftly, to move on in life. Under the situation of a Zombie apocalypse, knowing how my family is, I would hope we'd find each other.
Five years is a lot of time to hope... Grief is a terrible thing. I'm not saying I would move on and I'd be ladeefreakingda with my life, but I would have to move on or I would die with the past. I'm just coming from a place that I know from experience, even if you have five minutes of denial of how it can't be real and how you only just saw your friend/family member/ pet dog, and they were fine/whole/healthy, after a while you have to just let it sink in.
I also feel that if I'm trying to get in touch with them, they must be doing the same with me. It won't be "sorry your 'princess' is in another castle"
now that I've mulled over this response before posting it, I will watch something happy.