Jennifer Lopez says she and Ben Affleck didn't break up the day they postponed their wedding in 2003 ... instead, they split well into the aftermath of the stunning delay.

The singer-songwriter spoke with Zane Lowe during an Apple Music interview and revealed the couple may have been headed down the path to breaking up when they called their wedding off, but they stayed together for a while later ... trying to make their coupling last.

JL said the wedding delay sparked doubt in both herself and BA about "what our relationship was and where it was going" and -- even though she knew she wanted to be with him forever -- she felt their marriage wasn't going to make it the distance.

Lopez explained they weren't "mature" enough to make the relationship work despite their repeated attempts ... and she added they were under the impression people broke up when "things get hard" -- so they went their separate ways.

Good thing too ... 'cause Lopez says they both needed to go find love and make families with other people before they could really work at being a couple again.

Remember ... in the time after "Bennifer" broke up and before they reconciled, Lopez married singer Marc Anthony and had two kids while Affleck hooked up with his "Daredevil" costar Jennifer Garner leading to a trio of children.

Lopez said she and Ben both felt more confident in themselves as individuals when they got back together ... and this time the relationship seems permanent with the two officially tying the knot in 2022.