For that heart even to happen, Ivan has to be by the river, so if it isn't triggering, just check to see if he's at the bank. If he isn't there then you can't trigger it.
yeah but according to the schedule on the guide http://www.fogu.com/hm9/bachelors/ivan.php
he should be at the hotel area from 5:30pm all the way 'till midnight.
I tripple checked the info, and I was going on the right day/time/even weather. It still wasn't working. I didn't try the back way, just the main path. I'll try the other way and see if that works.
googled a bit and searched the forums. the only thing i found was a youtube video saying you have to enter the Hotel Area after 6pm(spoiler for link).
besides that...i can't think of another way to help you. Are you already far into the game? Maybe a rare glitch occurred which prevents you from activating it. If you are really desperate you might want to try lowering his FP back to a black level, although it has been confirmed multiple times that in order to view a certain heart event, your FP must be at least some number.
my brain is starting to melt
sorry but that's as far as my knowledge goes