The government, at least the rightwing parties in it, want the Likud to support the bill so it will pass. The law is one supporting the soldiers, so the Likud should support it, and many in the Likud want to. The Likud though has to play politics, and they dont want to be seen as supporting this government, but they also dont want to be seen as voting against the soldiers. 

What makes it more complicated is that UTJ and Shas heard the calls within the Likud to support the bill and got all nervous. They threatened the Likud that if the Likud supports the bill, they will stop being loyal in Opposition to the Likud.

UTJ and Shas are now being accused as being "anti-soldier", which maybe they are in some ways, but really it is just politics. UTJ and Shas could have gotten plenty of things form this government had they played this type of politics, but they chose to stay loyal to the Likud and the Opposition and oppose the government, even when it hurt themselves in the short term. They see it as a longer term goal of opposing the government and coming back to power with more sway because they backed the Likud all along and stayed loyal. The Likud is in a bind. They cant vote against the soldiers, but they also cant turn their backs on their own most loyal partners.

And this is why, or at least one of the reasons, so many were upset with the Likud - they are beholden to Shas and UTJ and have to do whatever UTJ wants, even against their own interests. To be fair, Bennett is sort of in a similar position now with RAAM and Mansour Abbas, but the Likud has been doing this far longer and is inherently a far more powerful party that should not be beholden to the demands of smaller parties.