The 28-year-old is yet to agree new terms with the Cherries and failed to return for pre-season training earlier this week.
"Shaun hasn't turned up and Shaun is out of contract," Groves told BBC Radio Solent.
"At this moment in time we haven't come to an agreement and I think that's proving to be difficult.
"Everybody is different and everybody takes their own view of things as an individual and a player.
"Shaun needs to feel that the deal offered is right for him and at this moment in time that is not the case."