In the comics, Barry Allen and Iris have a complex relationship. Sometimes they face challenges and separations, but ultimately, they often find their way back to each other.
Maybe in the fanfiction, Flash discovers Peter's identity in a very unexpected way, such as seeing Peter's Spider - Man suit by accident. He then has to decide whether to keep the secret or not. He might struggle with his own jealousy towards Peter and the newfound knowledge. If he decides to keep it a secret, it could lead to an unlikely friendship between them, with Flash helping Peter in small ways without Peter knowing it's him.
Iris remains alive in the Flash comics. The creators have kept her as an important and ongoing presence, and her role continues to evolve and contribute to the overall narrative.
The survival of their friendship is uncertain. Oliver has a lot of pride and Barry is his friend. Finding out about the kiss could shatter Oliver's view of Barry. However, if they both value their friendship more than their feelings for Felicity, they could work through it. They might have to go through a period of awkwardness and rebuilding trust, but it's possible for their friendship to survive.