Alignment on Id and EPUB

There are no tabs in EPUB (or HTML) so that closes most doors for this. I'd try setting the style to Justified and putting a nonbreaking space between each of the two-word elements, leaving a regular space in the middle to "spring" apart.

And that will work only  — you guessed it — if the reader decides to handle the justification that way.

The other alternative would be to use two paragraphs with two styles, and collapse spacing so that they end up on the same line. This trick works in ID if you juggle things right, and might work in EPUB. I can't remember which style should have a zero leading to make the lines overlap; you'd need to experiment.

The most absolute method would be to use a table with two cells, defined to have invisible borders, and use two styles to push the text left and right.