You do not need a "clear rejection" to make something harassment. If I've never spoken to someone but I spend ten minutes a day staring at her chest, that's harassment.
If I ask someone out, they say yes, and keep rescheduling 100 times, me continuing to ask them out and not take the (subtle, non-obvious) hint is still harassment.
If I ask someone out, they say yes, and keep rescheduling 100 times, me continuing to ask them out and not take the (subtle, non-obvious) hint is still harassment.