
Has she had a season, if not then this may be the start of it, they can become more clingy but should be encouraged to carry on as normal. Don't leave the 2 dogs alone unsupervised as she may turn on the pup if she isn't in the mood for his rough housing and he doesn't pick up on more subtle signals.
A phantom follows a season whether mated or not and most don't last the full 9 weeks but some do where they get milk and start nesting with toys which should be discouraged.