Not really. It's not like she was actively seeking Jack out when she was in a relationship/married 🤷♀️
The way I see it - she & Jack fell in love. Iceberg played spoilsport. She survives, finds someone else that she loves, has kids & grandkids. And thanks to the necklace, she's reminded of her young love. All of which except the iceberg part sound very normal to me & not "slutty".
Is it weird to remember the good times you've had with an ex, when you're with a current partner? To me, it's okay, because it's not a direct comparison- who you were is different from who you are now & it's just a memory.
But different people may view this differently, maybe as cheating.
(And I know you're not judging 👍)