You could also use a pattern to match 1 or more characters except for a comma using a negated character class [^,]+ before and after the comma:

string pattern = @"[^,]+,[^,]+";
string input = "This,is,an, example,for,the,stackoverflow,community";
foreach (Match m in Regex.Matches(input, pattern))
{
    Console.WriteLine(m.Value);
}

Output

This,is
an, example
for,the
stackoverflow,community

You could do something like this:

var s = "This,is,an, example,for, the, stackoverflow, community";

var a = ("," + s + ",").Split(',');

//  requires using System.Linq;
var b = Enumerable.Range(0, a.Length / 2)
        .Select(i => $"{a[2 * i]}, {a[2 * i + 1]}".Trim(',', ' '));

Range enumerates the resulting array and computes concatenations of the corresponding pairs of strings.

Using Enumerable.Chunk from .NET 6, you can

• split on ",",
• create chunks of two items each and
• re-join those chunks:

string input = "This,is,an,example,for,the,stackoverflow,community";

var output = input.Split(",")
    .Chunk(2)
    .Select(chunk => string.Join(",", chunk));

foreach (string s in output)
    Console.WriteLine(s);

fiddle

If you're stuck with the "classic" .NET Framework, here are chunk implementations for .NET < 6:

• how do I chunk an enumerable?