I think Matt will hang around, I believe he's in it for the long haul.
Being a perpetual optimist, I think he has the best kind of personality to take this in stride, support Tiffany, and figure out ways around any limitations that will arise due to surgery.
That's the nice thing about an optimist, they see circumstances as glass "half full". He'll figure out what works and work to maximise their focus on that in terms of mind, body and deeper spiritual connection and experiencing happiness together.
I think he can help her enormously, to soothe her and reassure her that it will be okay, they'll work it out. That's my relationship prediction, worth what you paid for it...