What did Watson see as he looked through the window of merripit house?

From the text:

The night was very dark, so that I can hardly imagine how he could have hoped to see anyone. It had struck me that it was possible that some love intrigue was on foot. That would have accounted for his stealthy movements and also for the uneasiness of his wife. The man is a striking-looking fellow, very well equipped to steal the heart of a country girl, so that this theory seemed to have something to support it. That opening of the door which I had heard after I had returned to my room might mean that he had gone out to keep some clandestine appointment. So I reasoned with myself in the morning, and I tell you the direction of my suspicions, however much the result may have shown that they were unfounded.