UnlikeDonald and Melania Trump,Mike and Karen Pencedidchoose to attend PresidentJoe Biden’s January 20 inauguration.

Alongside his farewell words, Pence attached four photos from his time in office.

Conspicuously absent from his words or his photos?

Mike and Karen Pence at Biden inauguration

The former president of the United States, Donald Trump.

Why did Mike Pence ignore Donald Trump in his farewell tweet?

Pence was livid, too.

Mike Pence with Donald Trump

Mike Pence, of course, may have had another reason for snubbing Trump than his temper.

So too, may be Trump, or one of his family members' campaigns.

If so, Pence’s farewell snub is likely to become one of many.

The two former allies may soon turn into staunch political adversaries.