Have you ever stop and think whether it really is possible for
two people who perhaps know each other for more than 4 or 5 years,
to actually have feelings for each other later on?. Like maybe just
one day you see two of your long term friends become couples
instead. Sounds a lil weird, but what do you think? 
Yes, it can happen. There can be more than one reason for it
happening, but just to answer your question the possibility is
definitely there.