I think that he is beginning to attempt to start trying (phew!) to define his relationship with Jack.
Actually, I agree very much with what you are saying. To me, Ennis clearly has an intention in this conversation. He
wants to talk about them/their relationship/his fears. He asks
three times. First he asks whether everything between Jack and Lureen is normal. Not: if everything is all right, going well, they're happy together or whatever. No, he asks whether it's
normal. Why should it not be normal? Because Jack is gay.
After Jack reacts only casually (and lying, I agree with this opinion, and I also agree he lies with good intentions, to not upset Ennis), Ennis asks a second time, he digs deeper "She never suspects?" Again: what could she suspect? Well, the same thing Alma found out.
Again, Jack just shrugs it off. Ennis then really lets his hair down in his third attempt, the question about people on the pavement
knowing .
I think this scene was a rare moment of truthfulness and openness for Ennis, he's practically saying they're gay. I think the "not queer" denial is past him at this point. He has figured it out. He turns to the only human being in the world he can approach with his thoughts and fears. He's looking for reassurance and guidance from Jack - but Jack has his own (understandable) agenda and fails to react appropriately. Missed chance, again.