According to The Sun, Gwen will move into the property's cottage after struggling to meet mortgage payments on her own house.
"Gwen has been struggling with repayments on her home over recent months," a source said.
"She's re-mortgaged the property a number of times and now owes more than the value of the house."
The insider added: "Rob couldn't face seeing her struggle any longer, so he invited her to move in. Gwen had been reluctant to accept his help but realises she has to."
It was recently revealed that Williams proposed to Field using a pack of cards.