I agree that a widely-spaced screen like this can look "odd", although if it's consistent with the rest of the UI this may not be as much of a problem (and for that reason I can somewhat understand your reluctance to alter the layout).
To me, the biggest problem will be that in trying to click one of the Action elements, it's too easy to "miss by one" and click on the wrong line.
Part of Maisa's answer offers one solution: shading alternate lines will help minimise clicking on the wrong one. However, if you feel doing that would break consistency with other screens/cards, an alternative could be to shade the whole of a row when the mouse hovers over it. That way, as you approach the Action button on the right, you'll be able to see easily which item you're about to affect.
(Of course, hovering doesn't work on a phone/tablet. A phone's display is probably narrow enough that the wide-spacing won't be a problem; for a tablet you could make tapping on a row highlight/shade that row which would achieve a similar effect).
First you need to consider that the "items" might have a longer text. So let's keep that in mind and if users have longer text, then it might look good ;)
Then your action should look like a button (what is it exactly?).
With only 2 columns, that is the best you could do.
If your list is a list of action, you could include a deadline column on the left of the action button/call to action.
Hope that helped.