why we can't be together

In biology lesson we were taught about why some animals can't propagate. One reason can be spatial separation. It's when they just can't meet each other because they are in different places.

That physically and mentally distance between us is killing me. It feels like there is a wall that prevents us from loving, sharing a touch or a smile.
Maybe that's why we couldn't be together.

Another reason is behavioural isolation and it means that some animals are similar but they don't attract each other.

Do you remember the first time we met? You were one of those charming, confident and mysterious guys (almost) every girl was falling for. I was that simple, serious and suspicious girl that put everything in question.
All of the vain and dreamy girls were attracted by your appearance and only a few chess-playing nerds and super-intelligent bookworms ever had a crush on me.
It's not typical for people like us to prefer or even recognize each other.
Maybe that's why we couldn't be together.

Temporal isolation. It's very simple. Some plants aren't able to intersect with other plants because they flourish in different times.

While you were running through town to meet one of thousand girls I was sitting there reading a book. It was only one look we shared, but no word we spoke. It seems like every time we could have the chance to talk something comes in between.
It's just bad timing for us. A simple reason.
Maybe that's why we couldn't be together.

Ecological isolation.
Yellow foxglove and red foxglove are both on the same place but they both need different kinds of soil and so they can't ever intersect.

I can't give you what you are looking for and so you can't. It sounds hard but we just need something completely different, we live in two worlds.
Maybe that's why we couldn't be together.

There are too many things against us.
Like the nature personally wants to tell us that we just don't belong to each other.
And we do what we're taught.

That's why we can't be together.