If you've seen the episode and don't want a recap, skip to the next bold title.
The most recent episode of [The Flash](series:1068303) (episode 15) was a roller coaster from start to finish, most importantly the last 6 minutes. In the episode during a "double-date" you can see tensions start to build between Eddy towards Iris along with Linda towards Barry, as Linda and Eddy don't truly believe that Barry and Iris are truly over each other.
Joe is attacked at the station by Mark Mardon (Weather Wizard) because Joe killed Marks brother Clyde Mardon (episode one). Now Joe wants Barry to protect Iris just in case Mark goes after her for leverage.
Ever since Joe said what he did about Harrison Wells not being who he said he was to Cisco, Cisco has been thinking about why his forcefield containing the Reverse Flash failed even after he triple checked the schematics.
Cisco then goes and tests his forcefield to see if it was tampered with, while Caitlin is distracting Wells by taking him out to breakfast. As Cisco is checking the forcefield he sees the Reverse Flash appear in the forcefield. Startled at first he then realizes that it was just a hologram.
Shortly after Harrison Wells shows up out of know where standing up. He then goes on to explain that his real name is Eobard Thawne and he's from the future. He says the reason he wants Barry to keep on going faster is that the faster Barry gets, the closer he is to getting back to his own time. He explains that Cisco was like a son that he never had, with which he goes on to kill him.
Now Mark Mardon has captured Joe and has him on a boat just outside of Central City so he can watch Mark destroy the city with a tsunami. Barry and Iris are together when Iris reveals her feelings toward each other and Barry reciprocates the same feelings.
Shortly after this kiss they see a tsunami heading for the city. After a quick call to Caitlin, Barry knows that he has to create a wind barrier between the city and the tsunami to stop it. For having no excuse to why he's gonna leave so abruptly to Iris, Barry decides to reveal his identity to her. He doesn't even wait for a response from Iris before leaving to save the city.
As the Flash is running to create the border he runs so fast that it rips open the fabric of time and sends him back in time. Before any of these events even happen.
How Barry Allen can change everything that just happened.
With Barry Allen just coming from the future, he knows how to change things and how he can fix what happens. But what he changes will ultimately change for the better and some for the worse.
The way Barry can change things for the better is him unknowingly preventing Cisco from dying. He'll be doing this unknowingly because he doesn't know Cisco has died, he doesn't know Harrison Wells is bad and from the future. I don't know how he will be doing this we just know it's gonna happen based on trailers that show Cisco.
I believe Barry will go and tell Iris about his feelings for her prematurely based solely on the fact that she said it to him in a life and death crisis. I'm not saying that Iris doesn't have the feelings for Barry like she says she does, I'm just saying she had a reason for saying that at that time, and she probably wasn't thinking of Eddy or Linda at that moment. With this not happening as it had happened before that means Iris doesn't figure out Barry is the Flash.