I’m sorry to hear about this.
Two piggies need to be compatible to be able to form a bond and live together. Buying a piggy means you don’t know whether the two will be compatible so there is always a risk they won’t like each other and won’t be able to bond. In that case, the two piggies must live in separate but side by side cages so they cannot fight but so they can still talk to each other through the bars. Single piggies can’t live in separate rooms otherwise they will both be lonely without the through the bar interaction.
Living as neighbours is fine in the case of failed bonds where you are already committed to the new piggy (ie you bought from a pet shop instead of from a rescue centre) , but you are ideally looking for a compatible friend and that they can live in the same cage
The best way to find a friend for a single piggy is to have a rescue centre help you find a compatible friend. Some will help you with the bonding process so you can be sure they like each other before you bring a new piggy home. Others won’t, so you bring the new piggy home, try the bonding yourself and if it doesn’t work, then the rescue centre will take the piggy back and you can try another. If you carry out any bonding yourself at home, then there is a specific process you need to follow and it must be done on neutral territory.
You can get Wilbur a female friend but only if Wilbur is neutered and six weeks post op safe and infertile. If he isn’t neutered, then a sow cannot live in the same cage with him until you had him neutered.
Having an unneutered boar living side by side with a sow is risky depending on your cage set up - boars become very determined to get in with sows so any cage an unneutered boar lives in needs to be very secure to stop him from escaping/climbing over the bars, and getting in with the sow and causing a pregnancy.
Neutered boar/sow bondings also comes down to character compatibility so you need to find a sow who will accept Wilbur, again if you have a rescue centre you can turn to, then they are best placed to help you find a compatible piggy.
For future information, baby piggies shouldn’t be quarantined. If buy a piggy from a pet shop but the piggy is under four months old, then you don’t quarantine them as their social interaction is more important. You simply have to take the risk of having to treat both piggies should the illness be contagious.
Any piggy which is over four months old can be quarantined. Quarantine is done in a separate room and must be for two weeks (unless piggy is not coping being alone in which case again, you carry out the bonding and accept you may need to treat them both).
Piggies from reputable rescue centres should have already been quarantined and you can therefore rest assured that they are not carrying any illness. You can also be sure that any sow is not already pregnant (buying sows from a pet shop does come with the risk that they have not been separated with boars early enough and could already be pregnant)
The guides below explain everything further.
Bonding and Interaction: Illustrated social behaviours and bonding dynamics
A Closer Look At Pairs (Boars - Sows - Mixed)
A Comprehensive Guide to Guinea Pig Boars
Sows: Behaviour and female health problems (including ovarian cysts)