The mother surely should have discussed her suspicions about her son's sexuality with the father by now...
Big obvious lack of communication on her part, and the son is getting distressed over it. Father's there just trying his best to support a teenage son he doesn't know as well as he could, not knowing he's stepping on all these landmines. It's going to make it impossible for the two to bond properly unless the son comes out, which is too much of a burden to push on him.