Hi!
I’m not a huge expert (in the middle of bonding my guys myself) but a lot of that sounds pretty normal. He is most likely slightly territorial (chinning and digging at the towel that smells like her) as its always been his space. But it doesn’t sound overly aggressive. Sometimes you wont know until you try your first face to face “bunny date” – but you aren’t there yet.
So what you need to do now – to try and knock some of that territorial behavour out – is pre-bonding. (You can skip the bellow if you already know what that is lol)
Spend the next week swapping items (toys / litter boxes) between their cages… watch for reactions. If there is any, keep doing this until there isn’t. If no reaction, or the reactions have stopped, after that week you need to start fully swapping their cage/living space daily.
This will cause two things to happen:
1) They are used to the other rabbits smell everywhere
2) They start to lose track of what is theirs alone, as nothing smells like just them anymore.
Do that for about 3 weeks (so a month of pre-bonding total)
Then, depending on how they are reacting to swapping spaces, you should be ready to try face-to-face dates in 100% neutral territory.
** Biggest thing that helped for me was making sure it was somewhere where they couldn’t even SMELL their home turf anymore. When I first had them out together it wasn’t far enough away – so it was still “Semi-Neutral” instead of fully neutral.