I think both of them understoodd that there was a risk of not appearing normal, and each understood that marriage might have been a necessary cover. But Jack, I think, understood that marriage would always be a wedge to their plans for a sweet life. So he must have wondered whether Ennis staying single hinted that he was half-considering the possibility, and that this in and of itself, caused Ennis to take pause.
Jack still needed to be sure what was on Ennis mind..whether there is a slightest chance for Ennis and jack to live togetehr..if he gets married to someone else then there is no way they can live together or spend more time together...he was also curious of what the future can be like so he asked that qs...
I've always thought that there's a mixture of thoughts and sensations behind this question on the part of Jack:yes,he knew that a marriage had been the perfect cover for not appearing "weird" in front of this little and narrow-minded community.But,at the same time,he knew that this marriage had been an step back in his aspiration to share with Ennis something more than furtive moments they could rob every several months.What's more,according to how the new wife was,even these few days could be more difficult to spend...
Also he could be simply curious about how a person like Ennis,so afraid about what people could say,could risk himself on being object of gossips by his singleness.And,on a deeper stage,if in this denial on getting married,he(Jack) had something to do with;as a matter of fact,he needed to know-as you ,Smartestsonia,say very well-what was passing on Ennis mind,what he was thinking about the both of them for the future.
With a little of jealousy also behind the question,because,on one hand,Ennis wanted to remain single for not running away from his love;but,on the other hand,maybe Jack was afraid that not having a life together after so many years and being Ennis single,was because this last was beginning to be tired of the situation or(why not?) of Jack himself.I repeat,it's a mixture of feelings:curiosity,fear,illusion,jealousy,hope,...After all,Jack had to learn to be a very complex person because of the situation along the years.