My DH does prefer my hair long. But I don't keep it long for him (he hates tattoos and I got one anyway).
I keep it long for several reasons
I have A LOT of hair. And keeping it long weighs it down. I've tried a bob, I just end up with a massive bouffant.
If it was short, I'd need to straighten it every day to keep it under control. Not only is that bad for your hair, but I'm bloody lazy.
I like being able to throw it up without brushing it if I'm in a rush, like this morning when we all woke up at 0740 and needed to be out of the door by 0820!
I like the freedom to easily change how it looks. Braids, bun, high ponytail, down and straight, down and curly.
I can't bear having it in my face. So being able to put it up and get it away from me is the main reason. It's currently almost down to my bum, but I have gone as short as shoulder length. My main instruction to the hairdresser is 'do what you like, leave it long enough to tie back and get out of my face'.
Basically it's minimum maintenance. If I cut it really short, I'd have more maintenance as I'd need to regularly have it cut to keep it that length. As it is, I go to the hairdresser once or twice a year.