I sometimes ask my roommate what to wear...at the moment I'm undecided and have possible choices and sometimes her opinion is backed up with a reason that makes sense, sometimes its just her personal preference (sometimes we differ on style), and sometimes she just picks a random one because she just wants me to get dressed already haha. really, I just want all the input I can gather & then make a decision...if I choose against what someone suggested its not that I don't value their opinion, I just decided on something else.
Its kind of like flipping a coin...if you chose the heads side to do something, then it lands on head, its kind of like...oh well I would rather do whatever is on the tails side! You know what I mean? She asks you because she is uncertain and you telling her, will help her make her decision.
They're just trying to find an outfit that they think you'll enjoy. Sometimes that may go against the occasion they need to dress for or their personal taste. Some women do that anyway though I'm with you on the fact that if you're gonna ask your man's opinion and choose to go against it anyway then the girl should just not ask and rather trust her own choice.
just ignore it. it is a very trivial matter. sometimes you ask for a person's choice but you might feel differently. your mood might change or you might think that something else is looking better on you. no big deal