I've noticed many of the examples are Zero Context Examples. They are listed in a "boy/girl meets X" format, without giving any details about the actual reveal moment the trope is supposed to be about.
I suspect it's turned into a clone of Interspecies Romance, with people listing any two romantically involved characters of different species even if the characters knew about each others species from the start, but I'm not sure because I'm not familiar with most of these works. Someone that has seen these works needs to check to make sure the examples qualify, and if they do, give more detail about the actual reveal.
Not a Cat
I'm tempted to add an El Goonish Shive joke here: Boy meets Squirrel. The problem is that it doesn't really fit the nature of the page.
In short: TV Tropes Is Not Your Porn Stash
Could this trope extend to close friendships? Because I have an example in mind that plays very much like this trope, except the two characters were friends, not lovers.