Arranged marriage doubt – okay with her past, but how do I know she’s truly moved on?

I want to be very clear upfront:
I’m completely fine with her past relationships. Everyone has a past, and that’s not an issue for me at all.

The only thing that scares me is this:
How do I know if she has truly moved on emotionally from her ex?

I don’t want to marry someone who is:

• Still emotionally attached
• Still texting / calling an ex
• Keeping emotional backup connections

I believe past should stay in the past after marriage.

So I wanted to ask guys (and women too):

• Are there any signs that show someone hasn’t fully moved on?
• How can you sense if she’s still emotionally connected to her ex?
• Is it better to ask directly, or observe behavior over time?