The 24-year-old proposed to his other half in New York city.
"So first it was the shoulder. Now the knee could do with a bit of rehab," he joked on Twitter while sharing the happy news.
The couple have been dating for over four years, and live together with their pet pug Yogi.
Marty's team mates Ian Madigan and James Tracy were among the first to congratulate the happy couple on social media.