Most people say falling in love is something you have no control over whatsoever and, in a way, you really don't. But that's not a good enough reason not to try and stop a heartbreak before it happens. When Natalie Portman's 'Alice' in Closer said that there's always a moment when you can decide if you want to fall for someone or not, I screamed "Bullshit!", but in truth, haven't we all had that moment when we saw our heart breaking sooner than not, yet we did nothing to stop it from happen?
Not trusting your gut is a foolish move, but it happens.
Then you have the signs. These happen after you've ignored your gut and still you feel uneasy when they show themselves, to the point that, one day, you will know for a fact that trying to have something special with that person will only result in pain. And no one likes pain. Well, some people do. But then again I don't give advice to people who enjoy pain because I just can't relate to that, no offence, yeah? Let's just say I enjoy being happy too much.
Now you've felt uneasy at first and you decided to ignore it - that's comprehensible. Knowing for a fact that the person is going to fuck up and still trying something is just jumping in front of a moving train. Now, I've had people telling me that they're better than everyone else because they know what's going to happen, they know it's going to destroy them, and even then they don't back away. That's all well and good, very Gryffindor of them, but then again my other word for Gryffindor is idiot. So don't tell me you're better than me because you're reckless and I won't tell you I'm better than you because I actually think before I do something. It's just what I do and it's my advice to people who think they've had enough of heartbreaks and stuff. There was a time when I'd never fallen in love and in those days I remember I used to say "I want to fall in love, even if it hurts."
Well, I had my fair share of hurting, let's just get to the loving, shall we?
So when you see that train-wreck happening in front of you, what to do? Back away. No drama, no parting speeches, no epic last words. A friend gave me a very wise advice one day: never say or do anything that you've heard or saw in a film or book. Never say or do anything that you could perhaps see happening in a film or book. Keep it real, keep it dry and don't think you can change someone intentionally. Just say "This is not going to work. Goodbye." and add an "I hope we can still be friends." if you think you can handle it. Your super inspiring parting speech might make them rethink their ways, but it will never be honest, and chances are that your dryness has more of a chance of triggering their conscience than your emotional guilt-tripping talk ever would. Saying stuff like "I don't want to fall for you." will automatically sound like "I'm falling for you." and if you are then nothing's wrong with them, right? Wrong.
People only change genuinely when they do it for themselves, not for others - that's why you see so many people saying they're assholes because someone broke them and yet it only happened when they found out they couldn't count on that person in the first place, hence the person was not really there when the change occurred. See, they were the ones who decided to start being assholes in the first place and they are the only ones who can actually stop it.
So stop everything that won't do you any good. Stop trying to change people in order for them to make you happy and make yourself happy, for a change. Because after all those times trying to make other people happy and failing (because they weren't happy with themselves in the first place), it shouldn't be that hard.