Just from reading your last message, it's not clear to me why you want to contact D. Do you miss him as friend? As potentially more? It all feels very murky.
If it's not clear to me, it's probably not clear to you, or Seamus, either. Thinking about why you have a desire to be in contact with D again may shed some light on your motives, and can help address Seamus' fears.
Just a thought.