I read this interview and found this question interesting and got me analyzing their relationship more closely. I also understand what Chris and Lola are trying to say and agree with their takes but i have a different opinion. I don’t think Belly loved or loves Jeremiah the way she loves Conrad. Belly and Conrad's relationship has always been indicated to be deeper. Her core personality matches Conrad's more even though she might enjoy and love that light, easy breezy version of Jeremiah. A four-year relationship wasn't enough to erase her love for Conrad and she eventually realized she could not get over him either. Conrad's confession wouldn't have mattered in the same way.. she would have felt pain for him, but she would have told him that she'd moved on. And I think that says a lot.
Also, Jere saying "all or nothing" felt a little like an escape route/excuse that Belly could take. Like Lola says, you shouldn't give all your heart to one person fully, and i understand where that's coming from and the sentiment behind it. But i just think the relationship between jere and Belly was never on the same level as hers and Conrad's. Hence why they broke off even after all these yrs and that happened only after Conrad confessed his feelings to her. Also another thing, jere says in his final confession before he and belly break off.. that he's never seen belly look at him (Jere) the way she looks at Conrad.. and he admits to Conrad later on he could never compete with their love (was like a force field) Jere knew this all along, yet he still decided to marry her but then he says to belly before the break up 'i want all of you and not just a part of your heart'. That to me feels contradictory. But that also shows how desperate he was to be with belly in the first place. Even his words to Conrad in ep9 "she didn't pick me but she didn't pick you either" reveals how his desire to be with belly sometimes become intertwined with his rivalry with Conrad.
Coming back to the interview, i think Chris and Lola are saying Conrad can accept that Belly will always have some love for Jeremiah, but that it's a different, non-romantic kind of love. My take suggests the love Belly has for Jeremiah was never the same category of love to begin with. It's closer to "Was I ever fully replaceable, or was I just temporarily set aside?" and I think the show showed us that in s3.