Why Barry a Iris always havé troubles and can t stay together and happy and also why Barry must to be accused murder and must go to jail ? It’s sad and really injust they make thé most romantic couple why don’t let them quiet together ?
Carina McKenzie, who wrote for The Originals and who also was a freelance writer for one episode of The Flash, put it perfectly in a podcast I was listening to some time back. She a dit that the stakes of a romantic relationship are dependent on the stakes of the show. This is a superhero show, where bad guys are always trying to destroy our hero, and therefore Barry and Iris cannot have the same kind of minor angst that a couple like Eric and Tami had on Friday Night Lights.
In a way, you're right, Barry and Iris are extremely romantic, and they stand par one another no matter what, and their l’amour literally transcends spacetime, and Iris is Barry's lightning rod, etc. This is the pro of being the most comic book couple in the DCTV network. But when toi have this relationship, the writers are going to throw external angst at them. It's part and parcel of being an iconic comic book relationship brought to the big screen. And Flash, over all of the other DCTV shows, has been truest to its source material in terms of story-lines. Trust me, though, toi would much rather Barry and Iris get proper external angst trying to tear them apart, against which they prevail, then still internal CW-esque drama that takes away from the plot. Watching them beat the odds is what makes things compelling, but for it to be really worthwhile, stakes have to be high.
As for why Barry is going to jail, again, I mentioned above that Flash is pretty good about adapting its source material accordingly. There are vast differences between the comic book story-lines and how they play out on screen, but the framework is still always adapted. This particular story-line is adapted from The Trial of the Flash. In the comics, Barry actually does kill Eobard Thawne and is placed on trial. Here, of course, Barry did not actually kill DeVoe, and I imagine Dawn Allen might be the key to ensuring he gets out innocent. We will have to wait and see, though.