Chef Peter Cumming was told he must serve at least 14 years before he can apply for parole.
Cumming, 58, murdered Glasgow University worker Lynda Brown, 63, in the home they shared at Mannering Road, Shawlands, Glasgow, last September 1.
The High Court in Glasgow heard he snapped when Ms Brown said she had already eaten. He grabbed a knife and stabbed the mother-of-two four times in the back.
Sentencing Cumming judge Lord Bannatyne told him: "This was a pretty senseless crime, which has had a huge impact on the family of the victim.
"This was, in my view, a particularly nasty murder, a vicious attack on a defenceless woman with a deadly weapon - a knife. In this case the victim was entirely innocent."
The court heard Ms Brown and Cumming had planned a dinner party and invited two friends.
When Cumming returned after buying ingredients for the meal he claimed Ms Brown told him she had already eaten and this made him "really angry".
Cumming, who had an alcohol problem and who had previously been convicted of domestic abuse on Mss Brown, claimed they had had words and "something snapped".
He added: "I was in behind her in the bedroom and I had the knife and I don't know where it came from - I was out of control."
Defence QC, Gordon Jackson, said: "From the outset he has been willing to plead guilty to murder. He is hugely remorseful."