We should not expect to see him back anytime soon, but that's not what's important.
"The Canadiens have announced that Martin St-Louis will have to be absent for an indefinite period due to family reasons. I hope everything gets back to normal quickly and without worry. Trevor Letowski will take over in the interim." - Marc Antoine Godin, The Athletic
In any case and whatever the reason, we sincerely send a wave of love and positive vibes to Martin St-Louis and his family.
The most important thing is his family and their well-being.