Language / What does changing this name ending mean? [6]

Hi All,

I've been dating a Polish girl for a while and the relationship has become a bit strained with the distance as she is in Poland now for the next two years. While I was over at the weekend we had a talk about not being so involved but it was hard to say what we agreed on really. Her name is Dobrusia but she always signed off her name as just "d." in her emails. Her most recent one she has signed off as "Dobrucha". I have always had trouble remembering the maening of the different forms off her name. Does this imply that she is being more formal with me and trying to put some distance between us? I presume she is trying to send me the message with this but I didn't want to miss some other subtulty or take a meaning where none was intended. Any help would be great.

Cheers,
Liam