(M 28) brother (M 26) is getting married next week (I am a groomsman) and I know the general expectation is that I will cut my hair for the wedding. In fact I had agreed to it and went to do sona few weeks ago and that is where the problem begins. I have been growing my hair out with the intention of donating it to wigs for kids and had intended to have 2-3 inches of wiggle room after getting it cut. When the wedding date was announced I kinda figured it would be closer to an inch or so but whatever it would work I am not against having shorter hair for a bit. But when I went to get it cut the salon lady told me that even if I waited until just before the wedding, to get a length that would maybe be accepted (12 inch min, preffered 14 )would require essentially buzzing/shaving my head, which is not something I would like to do nor do I think it would look good for wedding photos so I did not get it cut that day, instead eventually settling on the plan to just have my hair pulled up and done professionally to have it as nice and tucked away as possible. I felt okay about this because I understood it to mainly be my dad who was bugged by my hair and in that case then tbh oh well. However today my dad mentioned my brother himself had talked about it the other night ( the bride's brother also has longer hair and apparently between the both of us there's been some conversations/concerns about it) and now I feel a bit torn about it. To cut it to what they're imagining would be getting rid of almost 2 years of growing it out just to look a certain way on one day. I plan on calling my brother this evening to hear his thoughts directly but AITA for not just getting it cut already? If he says it's just a preference WIBTA for going against it? Thank you for any thoughts/opinions.

UPDATE: Thanks guys, talked to my brother and don't think he's psyched but was accepting of the plan of keeping it "pulled high and tight"