Your predictions about the marriages of your friends are of the kind that have a high chance of coming true.

1. you have not set a timespan. If I predict my neigbours marriage will end one day, noone will want to bet with me because it's too easy. If I say that their marriage will end in 2010, it becomes a lot more interesting....
Also, have you realized what you did? Someday...that means you could die now. Or in 40 years. If you spend those 40 years living in fear you've wasted your life. That's worse than death.

2. you don't need to be sensitive to pick up signs that somehow a marriage won't work out. People are good in picking up the things that stir beneath the surface. Sometimes this happens on an unconscious level, which is why a lot of people react to events with an attitude of "I knew this would happen." It's called intuition and does not nessecarily mean you're psychic.

Don't get me wrong, I do believe there's more to this world than we're seeing and strange things have happened, but you must not get lost in it. I think you have set yourself up for an unnecessary fright.

If you believe these things happen, then you probably also know about the power the mind can have over the body. People can set themselves up for failure, get themselves scared and even sick, because the body reacts to the way the mind is operating. If you're living in constant anxiety because of your impending "doom" then this is going to have an impact on how you feel physically.

Do not confuse this as a 'sign.' In other words, it's fine to believe in fate, but to look to deeply into everything will make you blind to the world. Try to find a balance. If you do believe this is for real, track your past. Write down what else you predicted and how legitimate those predictions were. As in: how much chance did that prediction have to come true? What about timespans? If it was unlikely to happen, but you predicted it and it did, you might be onto something.

Still, don't let it get to you. Everyone dies. But how many people have actually lived?