It could be a sickly-sweet story about Twu Luv. It could be a story about the Sue using the poor Agent for her own nefarious ends. It could be somewhere in between, with the Sue worrying that he doesn't really love her - that it's her ex-suvian nature doing it to him. There's all kinds of interesting places you could take a story, and I don't think anyone here would object to any of them.

Love is subjective. It's as mysterious and individual an idea in fiction as it is in real life.

Good question.
I would it suspect to be at least something approaching true love, as agents are usually impervious to Suvian influence, and there is always the Reality Room to go and check how real this love thing is, if you have very practical characters...

I think there are a couple recruited semi-fic blip characters that have at least married other Agents. Not sure if you'd count pon farr in the True Love category, though.

Both individuals would probably expect to see some trips to FicPsych, some anti-lustin, and odd looks from other Agents. Concern about reformed Mary Sues going bad again does not seem unreasonable, as would caution to verify True Love over Twu Wuv.