Hey Gizmo,
The trouble with boars eh?
You know, even in stable boar<>boar relationships (and indeed even among sows) you will always get occasional flare-ups. The thing is that boars in particular are quite territorial and so little things can start fights. It's always safer to try to make sure that there is nothing to bicker over.
Unfortunately, even erstwhile stable relationships can break down entirely but there is little we can do about that. At the moment I'd say you can keep the two together and just keep an eye out for any major changes in their behaviour over a longer period. Occasional bust-ups are to be expected, just as I used to have with my own brother!