I was romancing Tali the whole time too. So I couldn't choose the Geth over the Quarians, for obvious reasons. Anyway I couldn't cause like I said, I lost Legion in ME2.
Her feelings don't change at all if the Geth are destroyed. The ONLY downside to choosing Destroy at the end of the game is losing EDI, which sucks cause she's awesome. Personally I choose to believe that she'll be fixed, just like the Mass Relays and Citadel are fixed. Tali will remain with Shapard if he survives and presumably you'd have loads of fun with her on Rannoch. So all is well, except the Geth are gone (in your case). My Shep goes down in a blaze of glory and Tali puts his name up on the wall, perfect ending for me, save for EDI, but she's getting fixed so I'm not too sad (kind of like Data at the end of Star Treak: Nemesis).
You're point is valid in that there's no Fairy Tale perfect ending available here. Someone is going down one way or the other. You CAN save the whole galaxy and make a perfect Milky Way, but that WILL cost you Shepard. If you think about it, it's a small price to pay, and I believe anyone would be willing to pay that price to save everyone. It's a poetic ending and I think Bioware had the same idea.
Mass Effect was about choices and hard decisions. If Bioware was going to put at least one life lesson in this series, it's that there's no such thing as a fairy tale lol