Honestly, I can understand how Tidus would feel a bit resentful over his father, but I think both him and his dad had some serious communication issues. Jecht was such a hard, masculine, blitzball badass that he unfortunately lost his...ability to show affection outwardly towards his son. He loved Tidus very much, but he just couldn't....show it in terms of actually just sitting down, patting him on the head, or just giving a hug. He always wanted Tidus to surpass him and be the best.
Likewise, Tidus never tried to understand or think about why Jecht pushed him so hard, and wanted Tidus to see him as a rival. Tidus was so quick to judge and think Jecht hated him or didn't give a shit, that he missed the obvious.
Despite how ones a whiner, and the other's a macho monster, they're both surprisingly similar. They both can't quite understand or express themselves properly. Which made their final confrontation and ending, all the more touching.