He could do with a fcuking shave as well. And they might give him some advice about the curtains.
Having said that, the haircut doesn't change the person underneath the hair. If you have a strong relationship you would expect it to endure. However you do need to be aware that two things WILL change your bf:
(1) The continuing process of growing older/maturing, and
(2) Basic training and the whole transition to being a soldier. His life will be completely different from anything he has so far known.
So you will need to understand the processes he is going through and the challenges he will face in the future. You will need to undersatnd the importance that his "mates" - his fellow soldiers - will have in his life, and the reasons why that will be the case. You will need to be able to support him through all that. Or perhaps you will need to be able to recognise that your lives are now headed in different directions.
Rear Party is a site that might offer you some support. Good luck.
Guys, I understand a joke, but I wanted to share something of this transformation with people who might understand. It's an emotional thing for me, and somehow symbolic too, because it makes his Army life seem more real to me.