"I want to know if it would be possible for your actions to influence the relationships of other characters? Like not only trying to get the girl you want but also help another pony with their love life(multiple path routes) such as pairing Rainbow Dash with Big Macintosh while you try to get the Fluttershy ending. I know this would be more work but I just wanted to hear your opinion."
Well, its possible.
According to Emil, Ren'Py, the engine we are using, has full Python functionality, which means this is possible, and easy to make.
BUT, this would put strain on the writers and artists, for the following reason.
To create all the possibilities, we would have to write 10^2/2 possible storylines.
So, in the end, your answer is possible, but a lot of work.