I really hope not. It would kill one of the purpuses of the show. Since they one the main story was the realtionship between Meredith and Derek. They may fight and all but i think in the end they'll work it out. Come on, any sane person can see that they are perfect for each other, they complete each other in a way that any of their anterior partners(Addison, Finn) never did. So, let's hope Shonda respect the chemistry between them and keep them together. Oh, and give them a baby for cry out loud. Meredith deserve to get pregnant again. Raise your hand who wants a McBaby? *raises both hands* at least I've been wanting for them to get pregnant since día one. Well, if it's for me, they will separate o divorce. Fingers crossed for that to never happen. :D
UHHH heck no! If they did they would just get back together like they always do. Derek will adventoualy forgive Mer and they'll get Zola back im sure of it. so realy there is no point of them breaking up.