Aha! That's cute! When you just began a relationship, you might overthink stuff because your love which is used to stay in your imagination is now becoming reality, and you might be working to reconcile fiction and truth. This would be a time when you realised she is not exactly what you thought...
Many who are married for some time would realised that it's not about compatibility but hard work. It's quite easy to bottle up emotions and desire in order to not "burden" the significant other. But that bottling up would backfire one day and become something which might seem like sudden...