How to tell if he's a keeper

A friend of mine recently watched the movie 28 Days Later with her boyfriend, and they ended up having the following conversation:
(for those unfamiliar with the movie, it's about surviving a zombie apocalypse)

Him: Man, why is he going back? He should be running as far away in the opposite direction as he can.
Her: He's going back for the girl. She's still there, maybe getting turned in to a zombie!
Him: She's probably already a zombie by now.
Her: Yeah, but he has to be sure. Are you saying that if I was possibly a zombie, you wouldn't come and at least TRY and rescue me?
Him: (joking) Babe, if you turned into a zombie I'd have to kill you! It's the only way...
Her: (very much NOT joking) I always knew you were a selfish jerk, but now I have proof!
Him: Proof? It's a zombie apocalypse! And besides, where are you? If you aren't a zombie then why aren't you trying to find me?
Her: This is the last time I ever do anything nice for you, because it's clear that you don't even love me that much.

I've had similar arguments. I had one boyfriend tell me, "I love you, but I'm not going to avenge your death if that's what you're asking." Well, I wasn't asking that, but now that we're on the topic, why wouldn't you? If I was murdered, I'd want my lover to devote his life to bringing my killer to justice. Sound demanding? Well, I'm prepared to put the same offer on the table.

The thing is, I don't want a mate who's only in it for himself. I want to know that he's going to be there when it gets tough, or scary. I want to know that when I turn into a zombie (usually when I'm stressed and haven't had any sugar that day), he's not going to run away. I want to know that he would do anything to secure my happiness, and sometimes, that means doing stuff that's difficult, or scary or just plain inconvenient.

Another friend of mine recently had a baby, and she said that once you have a kid, things can get real ugly, real fast. You need to make sure you're with someone who is there for you in a crisis.

In the absence of a baby, if you're trying to figure out if the guy you're dating is a keeper or not, maybe you just need to ask yourself, 'What would he do in a zombie apocalypse?' And if the answer is 'Run away', they maybe that's exactly what you need to be doing, right now.