] Isn't Bosinney a little thick skinned here?

Thick skinned is an understatement. I think that he is a total and absolute cad. He has ignored June for weeks, using work as an excuse. It's apparent that his affections are engaged elsewhere and he is no longer interested in marrying her.

I believe that an engagement was still a binding contract in this era, but I think that he could have asked June to release him. She might have tried to fight for him; I suppose that she could have said no. But I can't see June marrying a man who did not love her. And I can't see June (supported by her grandfather) suing Phil for breach of promise. So far, Bosinney is taking the cowards route.