it does bother me when people say "ARIEL GAVE UP EVERYTHING FOR A MAN" because that's really not what happens?
Ariel desires to be human long before she ever even saw Eric. In fact, the biggest demonstration of this, Part of Your World, happens before Eric. The film does conflate her wish to be human with Eric rather early on in the film, unfortunately, which i believe to be the biggest reason that the "she changed everything for a man!" argument comes up.
personally, i believe that up until about Kiss the Girl, Eric was just a symbol for Ariel. He embodied everything she believed/knew about the human world and her desire to be with him ("but Daddy, I love him!") was more about her desire/love of the human world as opposed to actual love for him. (of course, i also believe she was attracted to him on a superficial level at that time too so that's also icing on the cake)
I also believe that Ariel would have taken the contract with Ursula even if she'd never seen Eric. I don't think she'd have taken it just whenever, but if she and Triton had a fight, absolutely. Just like in the film, where the catalyst of her decision was not Eric, but Trition destroying her treasured possessions and, in her mind, dooming her to a life of unhappiness under the sea.
long story short, Ariel's decision to become human was not the result of meeting Eric, as he was merely another reason in a long list of reasons she had to become human. Ultimately, I think Ariel's story is one about how the thing that will make you happiest and your family will sometimes come into conflict, and you will have to make a difficult choice regarding both. The resolution of Ariel's story also shows that you can make it work, as she resolves the conflict and gets that what will make her happiest (being a human) and her family (showing her father that humans aren't all bad and uniting the two worlds)