The #FantasticBeasts COG Behind the Scenes Dumbledore featurette is perfect. What we find out:

1. Yates said that Dumbledore and Grindelwald drifted apart because "AD felt what GG was advocating ultimately was wrong" so if you think AD ONLY became the man he became because Ariana died, it's not. It's more complicated than that.

2. Yates: "There're scenes in the movie where I wanted to suggest that AD still held an affection for GG. That there was still a love between the two men."

Throughout this featurette everyone implies that they both loved the other and that it wasn't one sided

3. JKR on Grindeldore: "Like in any relationship, one never knows
what the other is feeling" and implied that she is interested in exploring the
emotions they felt for each other

Could this mean, in future movies, we could watch a conflicted Dumbledore and Grindelwald doubting that the other ever loved them? Could their journey, throughout this series, be to find out that they both actually did love each other?

Grindelwald to Voldemort before his death: "There is so much you do not understand"

Dumbledore: "If there is one thing Voldemort cannot understand, it is love"

Could it be that we learn that, unlike Voldemort, Grindelwald could understand love and it's importance?

Yates: "This is a relationship that is compelling and profound and authentic, this is a story about two men who loved each other and ultimately have to fight each other"

THIS MAKES ME SOOOO EXCITED FOR FUTURE MOVIES. BRING IT ON!