The singer-songwriter shared a pic of a young Ben to her Instagram story in black and white ... and small lettering appears, one letter after another, under it. The message reads, "Our Hero. Happy Father's Day."

She also tossed in a white heart emoji ... letting everyone know she's still got a lotta love for her husband of nearly two years who is dad to Violet, Seraphina and Samuel and stepdad to her kids Max and Emme.

BTW ... Jen also shouted out her own dad with a Father's Day post -- sharing a black and white photo of him as well, so Ben's in pretty exclusive company here.

Jennifer's sweet posts are an interesting sign for the couple who have been through the wringer recently. As we've told you, the couple separated several weeks ago -- deciding to live in separate houses -- though they've still put on a united front for their kids.

They've attended multiple graduations together -- though at his son Samuel's graduation, the two stayed far away from one another. Jen did go over to Ben's rental home after the ceremony but didn't sleep over ... not surprising given we told you the pair are hurtling toward an imminent divorce.

They're even trying to sell their giant Beverly Hills mansion ... though they're trying to do it on the DL.

The two have been spotted wearing their wedding rings in public -- albeit Jen more consistently than Ben -- and that, plus this message, is bound to give Bennifer fans hope of a larger reconciliation.

That said, Lopez has called out all the negativity in the world while rumors have swirled -- unclear if she meant about the possible split specifically, but it's certainly possible.