Wade, 30, first met his 24-year-old fiancée when she escorted him onto the stage ahead of a big match.
The seven-time Major winner has battled with depression throughout his professional career and concedes that he owes his life to Marsh.
He told The Mirror: "When I feel like jumping off a bridge, Sam is there for me."
Wade claims that he needed a drink to settle his nerves before 'asking' Marsh's father for his blessing.
He added: "I wasn't drunk, but I had a bit of courage and told him 'I'm going to marry your daughter and there isn't anything you can do about it'. Sam was shocked, but thankfully her dad took it well."
Marsh said: "We are so excited. It's going to be a big white wedding."