what would be needed or what would need to happen for that to work out?
Canonically a marriage between two baptized persons is a Sacrament. However, for a Catholic there are additional requirements regarding where you may be married and by whom.
For a Catholic to marry a baptized non-Catholic, the Catholic must receive permission from the bishop and must complete the Catholic sacrament preparation process, complete paperwork, and make a promise to raise their children Catholic.
If the Catholic wants to get married in the non-Catholic’s place of worship then they must receive permission from the bishop for dispensation from the Catholic form of marriage.
The priest who does the marriage preparation would be able to guide a person through the process.
That is the *canonical *requirement. However, it should be noted that the Church allows for mixed marriages but does not
encourage them. In fact, the opposite is true.
I would encourage anyone dating a non-Catholic to reconsider this unwise path.