To think about or talk about something in a way that is too emotional or too focused on feelings.
When people sentimentalise, they might not think about things in a clear or realistic way.
Examples:
She likes to sentimentalise about the past.
He always sentimentalises about his old toys.
Don't sentimentalise about things that are gone.
I don't want to sentimentalise about my broken toy.
She sentimentalises so much that she forgets what really happened.
He sentimentalises about his old dog all the time.