1. Set up your profile and preferences
2. Live, and wait for notifications that somewhere nearby a possible match is there
3. Go to your possible match and talk to him/her
so what do you think?
I can see two problems with this. The first is enforced synchronicity: I can't scroll through profiles when I've got a few minutes; if I want to make a match, I have to act on the notification right then and there. For users who live in large cities, the overwhelming majority of their notifications will occur when they're commuting, doing a food shop, eating out with friends, etc., which aren't great times for chatting up someone. The second problem is safety: users who misbehave aren't doing anything they wouldn't have done without your app, but because your app was involved, you're the one that takes the reputational damage.
There was an entirely tech-free attempt at this sort of thing called the Pear Ring, which was a turquoise rubber ring to be worn on a finger that indicated that you're single and ready to mingle. The fact that the Pear Ring website no longer exists and web searches only return lifestyle magazine websites telling us it's the future of dating suggest that it didn't work.
for example you go to an event and turn it on and thus make urself "matchable" so it would simply make rejection disapear
the difference between this and the pear ring is the simplicity of an app that you can download and start using instead of purchasing an extra item that you have to wear
If you think about how meeting new people currently works, there's a bit of sizing people up to decide what sort of chances you have or whether they're a creep before you decide whether to go and talk to them - I think that's the crucial aspect your idea is missing.
First, we're all going to be rejected from various things over the course of our lives. It's inevitable. Learning how to deal with it when it happens is a critically important life skill.
Second, isn't it better to know that you've been rejected than to be silently ignored? Being ignored without knowing why is a path to alienation.
Also, this approach doesn't eliminate rejection. At some point, presumably, you're going to meet the person for real. At that point, rejection remains a real possibility.