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Two boars need to be compatible to be able to form a bond - one dominant and one submissive. If they arent and usually it’s when both want to be dominant, then the bond will fail and they will need to live side by side.
The best way to find a new companion is with the help of a rescue centre.
If you don’t have that option and have to get another piggy from another source, then that’s fine, but you also need to be prepared for them permanently living separately if they bonding fails.
To give you the correct information though, bonding with boars is not done slowly. It is a one time event - you put them on neutral territory for several hours and see how it goes. If they accept each other and can form a hierarchy then they remain together from that day on. If they cannot accept each other and form a hierarchy, then the bond has failed and they will permanently apart from that day on.
They can live in side by side cages for a couple of days before bonding day to get to know each other through the bars, but it won’t determine whether they will be able to form a relationship on the bonding day itself.
What you cannot do is put them together one day, then separate them, then put them together the next day. This is not how bonding is done for boars. Each separation causes the bonding process to stop and they need to start right back from the beginning the next time meaning they never properly bond. It is also stressful for them.
For two boars, ensure the cage is big enough - that is 180x60cm or a 5x2 c&c (But no smaller than 150x60cm). Two boars together need a lot of room.
Bonding and Interaction: Illustrated social behaviours and bonding dynamics
A Comprehensive Guide to Guinea Pig Boars
Dominance Behaviours In Guinea Pigs
