I know technically they're messing with zooble here because caine sang it but besides them being much more focused on each other and being so in sync during the song I think it matches jax's real feelings for pomni. Maybe not marriage but he obviously enjoyed being with her enough to ignore his own rule about being detached until it was way too late. He's not acting rationally at all. He has this fascination with her and really wants her to be his partner but if she abstracts or otherwise leaves he's done. That's why he gets so frustrated and fumbles the act of not caring at the end. He's already too far in and now he's stuck waiting for what he was scared would happen.