As stated above I wouldn't give up on their bond just yet. A bit of spring/summer humping is normal in boars especially at that age and its easy for one to get a little over excited.
Usually when I notice a spike in dominance behaviour with mine I really strip back their cage layout. just a few very open hides such as bendy bridges, hammocks or blankets draped over part of the cage. I give them lots of hay, forrage and other things to keep them entertained. And I'm very careful to make sure there's 2 of everything and I respect the hiarachy more than normal.
When I notice one is being particularly picked on (usually my poor Rufus) its tempting to step in and try to break it up but you do have to leave it as long as possible. Sometimes I go in and give them a hay top up with extra forrage if I think rufus really needs a rest because everything stops for food and it can just give them a bit of time to cool off.
If it's only one that has injuries that's not a terrible sign because it shows they're not fighting back to the same degree and have probobly accepted their position in the hierarchy and thus its just a waiting game for the top pig to realise there position is not being threatened.
That said I have never had to separate and reintroduce mine so I'm not sure how well that usually goes but hopefully someone else will be able to shed more light on that.
