Alice and Tarrant (the hatter) becoming a couple seems like a crazy idea, but crazy is typical for the Alice in Wonderland franchise? Lots of people want these 2 characters to become a couple, but should they?
The Alice from the 2010 and 2016 films is a young adult so pairing her with Tarrant wouldn't be that messed up, but it would be weird. In the films Alice and Tarrant are very close friends. Plus neither of them have a boyfriend or girlfriend.
However I don't think Alice and Tarrant are meant to be a couple. I think they're meant to be best friends. They have a special connection, but I don't think they're in love with each other. In the 2016 film Alice risked the safety of Underland for Tarrant showing that she would do pretty much anything for him. The 2 of them live far away, but they're best friends. I think that the relationship between them is a type of relationship 2 female friends have. Alice and Tarrant have a strong bond and they have hugged each other. It seems like the relationship Alice would have with female friends. I think they have a passionate, but non romantic friendship that is sweet.
Overall I love Alice and Tarrant and their relationship, but I think they should be best friends, not a couple.