What would you think/do if your SO told you "I've met someone"?

[SooSad33]

If you are uncertain, then you ask them what they mean.

IMO, if someone says that to me, they mean it in a 'romantic', interest, kind of way.

if in another sense, usually you'd have a friend say something like ' Hey, I got a new friend'... or,  ' I met up with an old friend', etc.

[MissCanuck]

6 hours ago, ZebDed said:

I mean, if my gf told it to me, I would know what happened and I would definitely end it and cancel all plans I had with her. So why would someone not get it?

Because love and denial are a powerful combination.

When you're in love with someone, it can be very difficult to accept reality. Many will try to sweep such revelations under the rug or convince themselves that it isn't really what it seems, because the truth is just too painful. 

Is the girl you're interested in hung up on some maybe-cheatig boyfriend abroad?

[WalterSobcha]

This seems very specific for an entirely "hypothetical" question.

Does it even matter if the person has cheated or not? It clearly means it's over.

[Capricorn3]

10 hours ago, ZebDed said:

It's a hypothetical question, that's all

Sounds more like you are looking for some more drama in your life.  You seem to thrive on drama, but all it does is give you a lot of anxiety ...... all of your own making.  It sounds exhausting.  OP, you need to chill and be happy within yourself if you want a healthy and successful relationship.