"However, Kristen won't give up Bear in a hurry. She helped Rob save Bear from Parvo disease [a highly contagious disease which causes death in 91 per cent of cases when left untreated], which nearly took its life when it was a puppy.
"She wants joint custody - and it could get a little messy."
Before news of Stewart's fling was revealed, the couple had been planning to adopt a second puppy.
The source added: "Robert and Kristen were looking into the possibility of adopting another dog. They were desperate for a play pal for Bear and scoured petfinder.com, as well as a few high-kill shelters in Los Angeles. But it seems that's out of the question now."
HEARTBROKEN ROB HAS 'NOBODY TO TALK TO'
Robert Pattinson feels like he has had "his heart ripped out" by Kristen Stewart.
The 22-year-old actress - has confessed to cheating on Robert, her boyfriend of almost four years, with her Snow White and the Huntsman director Rupert Sanders - and friends say they don't know if Pattinson will ever recover.
A source told People: "The entire thing has been such a blow to Rob. Talk about having his heart ripped out. Rob just isn't going to be able to get past the cheating - one time or not."
This insight comes after it was claimed Pattinson, 26, feels as if he has "nobody to talk to" and has left friends worried by sharing his woes with fellow guests at the hotel where he is temporarily staying.
One pal said: "Robert has resorted to asking strangers out to keep him company.
"He went out for drinks with a woman staying in his hotel and he told her it was 'ridiculous' he had nobody to talk to."
The hunk has also been spending a lot of time alone trying to forget his relationship difficulties.
The source added: "He's been spending most of his days off just playing computer games."
Meanwhile, Stewart's betrayal didn't extend to a sexual relationship with Sanders, it has been claimed.
Her Welcome to the Rileys producer Giovaani Agenlli insists their relationship wasn't sexual.
In a series of posts on Twitter, he wrote: "I'll say right now what the manipulative media isn't saying ... Kristen Stewart did not have any type of sex with Rupert Sanders.
"the spin that keeps growing on this story is staggering. There was NO on set affair. Stop printing LIES (sic)"
He also hinted he knew her whereabouts following a "twitition" by her fans pledging their support to her following the affair.
He added: "Please don't ask how or where she is, or what she thought. Just know this: She saw the twitition, and the support video tonight. Thank you (sic)"
Stewart and Pattinson - who met on the set of Twilight - are believed to have both moved out of the house they share together in Los Angeles following the affair, and he is thought to have stopped talking to her.
- Bang! Showbiz
