What is your daily routine like with him? Sometimes I’ve noticed free-roam bunnies kind of settle into a routine and explore less. I’ve noticed with my own bunnies they are more active when they are penned for part of the day. Then when I let them out they run around and explore, chin everything, etc.
If his diet is OK (not too many treats, etc.) then he probably won’t become overweight, it sounds to me like he is just relaxed in his environment and is settling into adulthood. Some bunnies are more chill than others. 🙂
Some ways to encourage exploration and play are to have tunnels and hide-y houses that you move around and reconfigure, food puzzles, and clicker training. 🙂
When bonding with bunnies, they also tend to respond well if you play “hard to get”. So if you spend time on the floor in his area but don’t try to pet or cuddle him, he might approach you for pets. As buns grow out of their baby phase they tend to stop tolerating being held and may become a little more wary (think the teenage years), but I’m sure you will develop a strong relationship with him. 🙂
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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.