It's over.
我们缘分已尽。

Don't call me anymore.
别再打电话给我。

There's someone else.
我有了别人。

We're not meant for each other.
我们命中注定不适合。

旁敲侧击说分手

I need some time alone.
我需要一个人过一阵子。

We're better off as friends.
我们做朋友比较好。

You're too good for me.
我配不上你。

You deserve a better man/woman.
你应该找个更好的对象。