Very normal. I was advised by a friend to include our relationship story in the application from the very beginning as a proof of our relationship (amongst the other proof required) and I’ll say, it helped a lot, as our case was definitely not straight forward (husband was previously married, has a daughter from previous marriage, etc.)
Definitely write out a detailed timeline, with your own personal touch of course - how you both met & fell in love, how the relationship progressed to engagement (if there was one), and then marriage.