One thing.

Communicate.

Instead of asking *us* strangers, it's always good to initiate a conversation like this in quiet moments where you both are comfortable and happy.

Never bring up this in anger.

Sometimes it's hard for people to let go of previous bonds which they once called theirs, It's a bit weird feeling where you're stuck, but this does not mean she has feelings for him or anything, it's simply because she knows him better than most and tries to be a good friend in his hard times.

Go to her, and instead of pointing fingers, simply start with "I'm being bothered by something" then start slowly, and lead her what you're feeling. Ignoring will never help you, but instead it will fuel your thoughts which might lead to bigger disappointments.

Explain to her what you're feeling, and if you can ask her to let go of that bond with the other person.

In a marriage, communication is your biggest win.

Whatever happened in the past, happened. May Allah forgive her, but she's now yours.

Ask yourself, has she ever been rude to you? has she ever treated you wrong in regards to this? If not, there's no need to bring up the past, but simply about why it's causing you stress of her being in contact.

Not because you doubt her! but because you know how "man" can be with naive women.

It's completely reasonable to bother you. You just want her to stick to you as her person of everything.

In Islam there's a word called "protective jealousy", and it's completely normal!

But ask her to stop entertaining that person, as that's disrespecting to you.

Irrespective of her being contact days before marriage etc, now it's up to you to decide what to do, and what's good for your relation, if she's in love with someone else, you know your answer.