The Husband - "I found the same number calling and texting my wife a lot"

I found the same number calling and texting my wife a lot over several months. She admitted it was wrong and said they were just friends. She would stop and it did.

The other day i found his phone number in her email contact list I asked about that and she said she had to send him some kind of file, since then she deleted his contact info.

He is also married should I suspect something ?