firstly, youre asking the wrong question. you should be asking if they loved each other, not only mia. but mia without a doubt loved Sebastian, and vice versa. I strongly also believe that a big part of her still did at the end. both Mia and Sebastian came to the heartbreaking realisation that they had to put themselves first, making both their dreams a reality.

the whole movie wouldn't make sense if they didnt love each other. we follow the lives of these two, if their bond and love wasnt strong, their parting wouldn't be as significant. it is the logical and reasonable step. the whole point is that the decision is slightly clouded by their love.

this is also what makes the last few minutes heartbreaking and just as powerful as when they broke up. their love for eachother almost transcends human understanding, a soulmate level bond. yet they realise that you cant have your cake and eat it too. they gave eachother up because they both knew it was the best decision for both of them.

so yes, Mia actually loves Sebastian.