The best rule of thumb is make it short, show no nudity and just imply with them kissing in bed and fade slowly. I would exclude any descriptive things because I’ve found Episode to be a very hypocritical app when it comes to guidelines-- yes there are Episode Originals that have scenes that definitely would get a Community Author’s story removed.
So, keep it minimal. I can understand wanting to add it-- but, be careful how you present the scene. They can decide it’s against the guidelines and either remove the story, tell you to change it or even ban you if they feel it’s too far past what they deem as inappropriate for the app.