Everyone has things they want to keep to themselves. A dark secret about their shame when they drank too much and woke up with a bunch of prostitutes and an empty wallet, a story about their childhood because they didn’t want to talk about it with others, or something more tangible… like… a diary.

And Arthur honestly thought that since Marston had grown up and stopped being such a pain in the ass, stopped trying to read what was written in the diary, or ruin it just to spite Morgan, no one was interested in his book anymore. But apparently he was wrong.

And he realized this when he walked into his tent and found you sitting on his bunk, carefully examining the sketches on the yellowed pages. He just hoped that you had the decency not to read what he wrote in there.

“Whatcha doin’?” - The cowboy asked, raising a slightly thick eyebrow, looking at you in surprise.

For him, his journal was something... intimate or something. And these pages kept many times more secrets than he wanted, and was going to tell you at all. He certainly wasn't the kind of guy who would pretend that he didn't have any problems - in front of his partner, however, he didn't want to burden you with his emotions or baggage of pain and feelings. He had some pride.