Oh dear, why is my poor geranium's leaves turning yellow?
I'm so sorry you're going through this. I've never experienced it directly myself, but I think it might be because of how you've been taking care of it.
I'm absolutely certain this is due to overwatering! It would be great if you could check the roots and see if there's any rot. If there is, I think repotting the plant would be a fantastic idea!
Don't fret! Yellowing geranium leaves is usually just a sign that you've been a little too generous with the water. However, there might be a few different reasons why the leaves have turned yellow. Nutrient deficiencies and lack of sunlight can also cause the leaves to turn yellow, so it's good to keep an eye on these things. But don't fret! The most common culprit is simply overwatering. You might want to try watering less often.