Looking on the internet deeply has found these results:

family matters is the most popular phrase on the web.

family matter 1437,000 results on the web	family matters 1934,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
So Jane Doe pays 1,000 bucks to get into the hottest party in town because of a family matter. With all due respect, this is a family matter. Excuse me, sweetie, this is a family matter involving two of my sons and the family business that Lucious and I started with my $400,000. Says he wants a meeting about a family matter. It's a family matter now. This is a family matter, Mr. Harper. But you mentioned a family matter, and sometimes the personal may jam up the professional. Mary wants to retain Pope and Associates to manage a private family matter.	I'm suspecting that these "family matters" are at the center of this whole thing. Subject: Legal aid across borders in family matters You speak only in English and only about family matters. I've had some pressing family matters to deal with, but I'm here to deal with it now, and... Our actions are based on the conclusions of the Council of Ministers responsible for family matters that took place in September 1989. I have come for family matters. Be calm and patient, specially in family matters. Jefferson wanted only to get back to his daughter, but the Queen had family matters of her own.

family matter

1437,000 results on the web

family matters

1934,000 results on the web

More popular!

So Jane Doe pays 1,000 bucks to get into the hottest party in town because of a family matter.
With all due respect, this is a family matter.
Excuse me, sweetie, this is a family matter involving two of my sons and the family business that Lucious and I started with my $400,000.
Says he wants a meeting about a family matter.
It's a family matter now.
This is a family matter, Mr. Harper.
But you mentioned a family matter, and sometimes the personal may jam up the professional.
Mary wants to retain Pope and Associates to manage a private family matter.

I'm suspecting that these "family matters" are at the center of this whole thing.
Subject: Legal aid across borders in family matters
You speak only in English and only about family matters.
I've had some pressing family matters to deal with, but I'm here to deal with it now, and...
Our actions are based on the conclusions of the Council of Ministers responsible for family matters that took place in September 1989.
I have come for family matters.
Be calm and patient, specially in family matters.
Jefferson wanted only to get back to his daughter, but the Queen had family matters of her own.