I was never convinced by it. They didn't seem very compatible. Tidus' entire role in that relationship seemed like a heavy-handed commentary on religion, with Yuna not questioning anything until Tidus dropped out of nowhere and asked some really basic questions. It made Yuna come across as somewhat dense. I would've preferred it if she came to the realizations about Yevon on her own and Tidus just wasn't in the game. And I felt like Yuna warmed up to him and wanted him to be her guardian far too quickly. They only had a couple of conversations before then.

Plus, personality-wise, they were completely at odds. Yuna was very modest, Tidus was a loud jackass. Don't know what she saw in him. And now that I think about it, I don't even get why Tidus was attracted to Yuna. Did he just want to protect her?