You say you don't give lessons in love...
The Doctor has absolutely no idea whether or not Martha is in her room. She could very well have been making that journal entry from somewhere else in the hotel... or somewhere else altogether... but he's working under the assumption that she is, because he's found that wandering around the hotel in search of people doesn't work well for him lately.
Especially with Donna stalking him off and on to make sure he's not injuring his ankle further.
He's been lurking outside her room for a good five minutes now, before he finally decides yes, he actually is going to manage this, and knocks at her door. And then he shoves his hands in his pockets, and waits awkwardly for her to open the door. Or tell him to go away. Or something.
Especially with Donna stalking him off and on to make sure he's not injuring his ankle further.
He's been lurking outside her room for a good five minutes now, before he finally decides yes, he actually is going to manage this, and knocks at her door. And then he shoves his hands in his pockets, and waits awkwardly for her to open the door. Or tell him to go away. Or something.