You havent done enough research
Claremont established them as having had a romantic past back in 1980. They reunited for the first time since they first met as teenagers but realized that their time had passed and they could be nothing more than friends
Aside from a few interactions here and there, not much was done until they were reunited in Priest's Black Panther series in the late 90s. They acknowledged their feelings for each other and acted on it but he was engaged and they didnt go further
Of course with both finally being single, they took advantage of it and started a relationship which became a marriage around 2006
The only thing wrong about how it was handled the last time was rushing the marriage instead of giving their relationship more time in the spotlight. I find them refreshing. In the 70+ years that Marvel Comics has existed there are barely any black couples. It seems that a black character can only find love if paired with a white counterpart. Its sad that I can count the amount of significant black couples with one hand. Its good seeing black love flourish and Coates is handling them perfectly