On the EEA family permit form it asks:
When did you first meet X?
Where did you first meet X?
I don't understand what to answer here because we first met online on the internet. Or do we have to tell when/where we first met in person?
If it is possible, you could answer both. For example:
Online: 14 May 2017; In person 3 November 2018
Reading over the application for the residence card (pdf), I am left with the distinct impression that they mean to ask when you met in person, so if it is not possible to answer as above, I would put the date of the first meeting in person. This also makes sense because you will be asked separately when your relationship began, and you can use an earlier date than the date of your first meeting.
The most important thing is to be absolutely clear about the facts. If you think that your answers to the questions leave anything unclear, then you should include a clear written statement of the relevant facts. This will protect you against suspicion of deception. If you are suspected of deception, you can point to the written statement as evidence that your answers to the questions resulted from confusion about the questions rather than a desire to misrepresent anything. The statement should be short and simple. It could be something like
We met online on [date], and our romantic relationship began on [date]. We met in person for the first time on [date].