When online dating doesn’t turn into something more, it may have something to do with ignorance on your part.
You should never allow yourself to interact with someone on an online dating site over an extended period of time without knowing what that person’s intentions are.
Perhaps you finally did it, but the other party never followed suit.
You should never start dating someone from an online dating site expecting that it will be natural for that person to just take down their online dating profile at the appropriate time.