Didn't June also disapprove of his relationship with Julie. She even offered to buy her a house !
It's all looking like things were slipping away from Jeremy. And he knew it.
They wanted to give her a place to live so he would stop living in sin with Julie.
They stopped living together anyway.
They got engaged and June was glad because then they would not be engaging in sin together.
Because his family liked the idea he broke the engagement to spite them.
He clearly wanted to do things that displeased them as opposed to doing things to please them. That demonstrates a problem he had with them.
He expressed to Colin he didn't like how they were controlling his life he had big mental issues with them.