Separation of powers is the basic concept that is the foundation of the Constitution. The framers gave equal powers to the three branches in order to balance power.
This balancing act makes it difficult, messy and hard to govern, but that was the intent. It requires compromise by all.
If the president doesn’t like laws passed by Congress, he can veto them. If the president doesn’t get legislation he wants out of Congress, that means he was not persuasive enough or he did not compromise enough.
The Constitution does not have a modifier to allow the president to execute only the laws he likes and to not faithfully execute the laws he doesn’t like.
Alberto Vega, Miami