If you're with someone and you care about them, especially if you love them, then it is only natural to have a desire instilled within you to change for them, because it would make them happy. Therefore, of course I have changed myself for others, because it was their desire I do so, but I'm speaking about externally and not internally.
What I mean is, if a person I was with wanted me to start wearing blue jeans instead of slacks and it made them happier in life and being with me, because they felt I looked better in blue jeans instead of slacks and they liked how it made my butt looked in them, then seriously what does it take away from me to give in to their request. It is just appearances, and a person's self-esteem and self-confidence shouldn't be measured by what you wear or how you look, but in who and what you are.
My point is, when you're with someone you love and/or care about, and they ask you to do something like grow your hair out or change the way you dress, and they're doing it because they feel it would better who you are and not for a selfish or malicious reason, then in my point of view, if it doesn't do harm to me, then by all means indulge the one you love and care about and give them what they want. Especially, and I can't stress this enough, especially if they are doing the same for you, such as a guy asking a girl to grow her hair longer, and the girl asking the guy to change the way he dresses or use a different cologne because it appeals to their libido more, or even when a girl asked me to shave my beard, because it scratched her face.
Did not a painter once cut off his ear for a girl? We do many, many, things in the name of love, but as long as it is not affecting us in a negative way, then by all means, indulge those we love and adore, because in the end, shouldn't love and relationships be about compromise and communication and giving each other what we need, want, and desire. That really should be how it is in my view point. Again, especially, if it cost us nothing internally to give in to such indulgences.