I think Kujerra is probably the one Jecht interferes with most. But Golmos and Gabrishe probably also rank high on his list. He's really a closet romantic.

The reason I nominate Kujerra for being his main ship is because I'm biased because I can imagine Jecht developing a soft spot for Terra, similar to how he's very protective of Yuna.

I have no clue what his reaction to Tidus/CoD/Exdeath would be.