The star suffered the tragic loss of her baby six months into her pregnancy at the beginning of this month, but the devastating ordeal has only strengthened her relationship with builder Sam Cooper.
A source told the Mail On Sunday newspaper: "Lily and Sam had loose plans to marry after the baby was born but nothing concrete was in motion.
"Now they have decided they want to be man and wife as soon as possible. They realised through their grief that they absolutely adore one another and cannot live without each other."
25-year-old pop singer Lily has previously described Sam, 32, as the "love of my life" and the couple - who have been dating since summer last year - are said to be looking at a wedding in the county of Gloucestershire in England.
They are thought to be considering tying the knot at either Lily`s father, Keith`s home, or in the town of Minchinhampton.
The source added: "Lily is very close to her dad and she took him up on his offer of holding the wedding at his.
"She loves his country pad and she and Sam feel it is absolutely right for them to marry there. They want to be together after what they`ve gone through and see becoming man and wife as the light at the end of the tunnel."
Lily is not thought to have got engaged to Sam yet, but sources close to the star believe they will soon.