You could have a point there, Monica - it's difficult to ascertain just how much he would have related to his brothers, and in particular the one to which he was particularly close. I've read some very intimate examples of correspondence between male Edwardian siblings and friends, but without specific examples of their correspondence it's hard to say just how confiding he would have been on such intimate details. He doesn't seem to have been forthcoming at all with his female relatives about his girlfriend, but he did confide in his brother.
On some other details - such as the state of his ingrown toenail and the condition of his teeth - he was more than happy to regale his sister with the gory details...but then, she was a nurse.
One thing he did mention about the South American ports is that he didn't find the women particularly preposessing...but then, he also mentioned that one of the old South American hands was absolutely convinced that Moody would find a local girl, marry and settle down out there, as others had done before (including a merchant officer friend that Moody particularly admired).
The crew sign on sheets do not refer to marital status, Alysoun - you're thinking of the summary info on the bio pages here, which refer to marital status. This is not indicative of whether or not that had a relationship, only whether they were married. Lowe, for example, is also listed as single, although he was engaged when the Titanic sailed to the woman he married a year later.
I don't really have much to add about Moody's girlfriend at this stage - indeed, there's not too much more I know, beyond her name and her father's occupation. I don't know what became of her, unfortunately.
I don't think he was particularly shy, Alysoun - he was a bit bashful as a child when all his female relatives teased him, but if I were surrounded by a grandmother, aunts and cousins all making fun of me, I might be a bit bashful too! He had a rather self-deprecating sense of humour about his photographs, but that's part of his charm - I don't think he was too serious in asking relatives not showing them to anyone. He may have been self-conscious about his looks - it is noteworthy that he had problems with his teeth, and does not expose them in any photos (unlike his shipmate, Harold Lowe, who can often be seen grinning widely). On the other hand, we know he carried on conversations with female passengers on the South American run, and had a laugh at his own expense when he slipped the odd accidental expletive in with his patchy Spanish.