Yeah, it's interesting that it's OFFICIALLY noted here that she's his girlfriend, since we've only seen the two of them together once, and that was quite a while ago in the strip (when Nick went to the gym for the first time). Aside from that, the ONLY mention we really got of the situation was in the Cast page (which seems to be where we get most of our big hints for future storyline stuff, ie. Michelle's family being poor, which has only slightly been hinted at in a few strips thus far), where it says he is "warming up to the idea".
I, for one, think the Nick/Charisma thing is going to end up being one of the more fascinating and better things that crop up in future storylines. It works on almost every level: Romance, a guy moving on after his wife dies, then there's how AGGIE will take the whole thing (ie. mixed emotions; happy for her dad, but sad that he'd actually move on and somehow replace Melody in his life).
I also like the casual mention of how Charisma's hair looks like Melody's. DEFINITELY something that could come into play later, dramatically speaking.