I would say they could, and if she's finding life a bit hard going, I would be inclined to try and explore it further before she starts secondary school (and waitlists are so long, that would mean starting now). If there is something there, a lot of children who cope in primary can start to really struggle in secondary, when it all gets bigger and busier and more demanding.
Social struggles – can you pin these down at all? Does she perhaps not see the point of some social niceties? Have difficulty judging the give-and-take of conversations, so can dominate or be too quiet? Either a bit too intense about friendships, or perhaps the opposite, can seem at times like she's really not bothered, and that ends up cooling the relationship.
Chewing and picking at nails/fingers – any other fidgets? What about when she was a toddler or preschooler? Or any other signs of anxiety, perhaps? Or perhaps sensory-seeking behaviour (really liking/disliking certain fabric textures, certain tastes, certain smells, even activities like swings or a trampoline)?
A hard work person, hard to please (which does sound like she is maybe finding life a bit hard) – is there any pattern to this? Maybe in terms of liking things just so, having strong likes/dislikes, difficulty compromising with what the rest of the family wants? Or maybe it flares at certain times, in a tricky mood after school, or at the beginning/end of school holidays?
Equally, it could be 'nothing', just personality and a bad run of luck with friendships. Sorry, that's not entirely helpful.