Kinda contradicting yourself there man!

The OP never said anything about "putting his foot down" or putting a leash round her neck or locking her up in the basement so she couldn't go to the tattoo parlour. You're making some big assumptions about him - next thing you'll be saying he's an alcoholic wifebeater and would have given her a black eye if she kept going on about wanting a tattoo! How the hell was he supposed to "compromise" on this issue? You either get a tattoo or you don't - he told her he wouldn't like it and that it would cause him hassle when they're out together. That's neither "controlling her actions" nor "disregarding her feelings", it's just him telling her he wouldn't like it. How were they supposed to "compromise"? Temporary tat? Celtics t-shirt?
She not only disregarded HIS feelings, but went and did it on the sly without even having the decency to tell him "I see where you're coming from but I'm going to get one anyway".
It seems to me if she complains it's "voicing her opinion" but if he does it's "controlling her actions", and if she does something that he doesn't like it's allright, but if he tells her he's not happy about it it's "disregarding her feelings". I reckon this is about all the **** you had to put up with by friends and family who didn't like YOU getting tattoos more than about the OP's situation, because, frankly, the arguments you are making are contradictory and show a double standard that would seem ridiculous even to you if you took a deep breath and stepped back for a second there!
Personally I don't find tattoos unattractive (though I'm not mad about them either), but, although it's everyone right to do anything they want to their own bodies, I would expect to have a say in the matter if I was in a relationship with that someone. I wouldn't (and couldn't)outright forbid my girlfriend from getting a tattoo, of course, but if she went and got one over my objections that would show me where I stand in the pecking order of her affections, and if she got it without even telling me that she was disregarding my objections it would show me how little respect she has for me as well.