There are two reasons widely believed by many BB members on why I recommend spaying:
1) There’s a 70-80% chance of unspayed female rabbits to get uterine cancer by the age of 4. For health reasons, spaying can be seen as a necessity, as cancer progression/removal is very risky and expensive.
2) Bonded is a title earned, rather than an adjective. Although it’s possible for two unfixed rabbits to be bonded, it is very difficult. What you’re most likely observing are two young rabbits getting along because they have not begun acting on maturity hormones yet. When those hit, you may see fights, chasing, and potentially even mating (sexing rabbits is notoriously difficult, so you could have a male and female). If you want to have two rabbits, the best recommendation I can give is to have them both fixed so their hormonal instincts do not put either in danger. Even if the rabbits are siblings, been together since birth, etc., hormones change a lot when they occur. Since there’s no telling when hormones will hit (maybe overnight when you’re sleeping), a fight can occur very suddenly and you can wake up to bad consequences. A common recommendation is to separate rabbits until they are fixed, recover, given time for hormones to calm down, then go through the -formal bonding process-. You can find that information here: https://binkybunny.com/BUNNYINFO/tabid/53/CategoryID/9/PID/940/Default.aspx
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.