You actually need reasons? Well, here you are then!
Season 01
~They both have special digimon~
~They are the same age~
~They both have big brothers~
~They both have special crests~
~They look sooo cute together~
~Even Angemon and Angewomon look
good together~
Season 02
~They're always near each other~
~They STILL look cute together~
~They still have special digimon and crests~
~It's SOOO obvious!~
~HELLO? They care about each
other!~
More comming!