if/else loop with (almost) daily events
It's probably because entry.dayOfEvent isn't returning exactly what "now"|date_modify('+1 day') is returning therefore the comparison fails.  Maybe one includes the time and the other doesn't, for example.

You can see what each is returning by doing:

{{ entry.dayOfEvent }}
{{ "now"|date_modify('+1 day') }}


If they are different formats, then you can make the 2nd one match the format of the first by using Twig's date format method.