In The Giver, how does Jonas feel about eliminating true happiness and pleasure to also eliminate both physical and emotional pain in the...

Clearly, Jonas does does not like this idea at all.  This
is why he runs away from the community.

As Jonas goes along
in the process of receiving memories from the Giver, he realizes that the people of his
community have lost something very important.  He realizes that people in the community
have no pain, but he does not think this is worth the cost.  He feels very unhappy about
the idea that the others can never experience the things that he has
experienced.

Because of this, Jonas decides to destroy the
community by running away.  He knows that this will set free all his memories and the
other people will start to feel all the things he has
felt.

If Jonas liked the idea of eliminating true pleasure
so as to eliminate pain, he would not have run away.