Going general is a good decision. Congratulations for having that wisdom. The quickest route to attract anything is to know that it is done and eagerly expecting it.

Just a few notes to what you wrote. There is nothing like "meant to be", because you create your reality. If it feels bad to think that you aren't meant to be, then that isn't true. But you have the free choice to live that reality anyway, even if it "isn't meant to be lived" from a higher perspective. There is nobody who has intentions for you. There is only you.
And another thing: There is no "forever person". People act according to what you offer them from within. When you think someone is perfect for you and you will stay together forever, then that will be your experience for the moment of course. But the moment you start worrying about them cheating or leaving you are in the process to mold your forever person version of them in the cheating asshole version. It's never about them, it's always about you. So in the end, it doesn't really matter if you go for the old or the new person. What matters is that you take responsibility for everything that happens to you, because you realize that it doesn't happen to but through you. Become clear about what's cause and what's effect. Mind is always cause, reality is always effect. It cannot be any other way. Therefore it doesn't matter who your ex is dating, because the cause is still your mind. Your ex dating isn't the cause for you not getting back together, that's you.

In my experience, it's easy to attract someone new who is perfect for you. The problem is that if you haven't put the effort in before to get clear about how reality works and have practiced it, you will probably end up in the same space again, because you have still the same beliefs which lead to the same fears and the same result. So I wouldn't recommend to make it about the manifestation, but to always make it about yourself.