And let's remember, the only one who had to lose in this story was her.
If you mean she was the only one who had anything to lose in this, I very much disagree, & will cite below my major grievance with this episode as the reason why.
And really Data wasn't just "someone that isn't right " for her, is a machine that can't even fit in the human concept of romantic relationship
I think you're drastically underselling Data, & my main gripe about this story is that she is underselling him as well. Data has nothing to lose in this? I'd argue Data has much more at stake in this than she does. To her, this is just a few weeks of a not too serious romance, not even a chapter in her life, almost forgettable really. To Data, this begins as his 1st experience in long term romantic intimacy, which could shape his perspective greatly, & it ends with her rejecting him under the claim that she doesn't truly matter to him, which we all know is just not true, & he comes away from this tragically thinking he has nothing to offer in a relationship
Your argument smacks of the some here that want to label Data as not a real person, not sentient/sapient, not deserving of serving in Starfleet on those grounds, not deserving of the same liberties as everyone else... basically just a piece of mechanical hardware. What show have you been watching, I wonder? They tirelessly dispute all of that, continuously over the course of 7 years. It's literally one of the biggest character arcs on the whole show.
Data is not the android you think he is. He's the android they tell/show you he is, & that fictional android was designed to have emotions just like the others of his kind. He maintains close relationships with people already, & many of them understand that he is just as real in his life as they are. Even Troi herself has told Data in
Data's Day that he would have much to offer someone in a marriage. Well, how else is something like that ever going to take form than like this?
Data can't be invested in someone on a personal level? Tell that to Geordi. The death of Geordi, the loss of his friendship, the absence of his presence, would be undoubtedly experienced by Data, even more than we already see he is affected by the loss of Tasha, who he knew far less, & he could easily be just as invested in someone else
Jenna's problem with Data is that he's not the right fit for her. He isn't emotive
enough, which is fair, & reason enough to end things, but she framed it much more detrimentally imho.
I can't even follow the whole Data+Jenna = Nice guy fantasy thing. Data is a non-human. None of that applies. Star Trek explores non-humans in all manners of ways, & a lot of them are just as odd for it, Worf, Odo, the Doctor, Spock. These characters don't act in realistic ways. You have to suspend some disbelief into the premise they are using imho