E.U. was basically created, at an attempt of "can't we all just get along" reconciliation, as a result of all the big wars among the countries in Europe. There is this thinking now that, if the E.U. dissipates, then all the European countries are going to want to start wars with each other.
So, now, there is also this thinking that the E.U. might just want to economically punish the U.K. (which unfortunately POTUS Obama and Hillary said they may support this type of punishment), which may result in a war between the U.K. and the E.U. ... and since USA and the U.K. are probably the strongest alliance in this world (we're basically siblings) and siblings look out for each other, then ya can figure what happens next if E.U. decides to economically punish the U.K.
I think a slight, bit, tremendously radical to think "This Means War".
...but I think that is where your husband is coming from...