Normal? What if? For sure.
Healthy? I think that all depends.
If you're looking at it like 'This is what a normal thing to expect -from a normal person, in a normal environment- is & was.' then I'd think it to be pretty healthy. What IF he'd been a normal/ decent/ ordinary person? What if I'd been right about his character, instead of misjudging? What can I expect from normal people, now? What were my expectations then? It provides the context. You didn't sneak him up to your dorm room with the expectation of trauma. 999 times out of 1,000 anyone who you would have snuck up to your dorm room would have done exactly as you expected. A fun evening. Whether that's totally platonic laughing whilst playing Boardgames & bitching about professors, or romantic & consensual, those are completely rational expectations to have when inviting a friend into your home. That they treat you with respect.
If you're fantasizing / trying to replace bad memories with make believe? Then not so healthy. What happened, happened, and no amount of pretending otherwise will change that. Ditto a lot of other similarly unhealthy thought processes (blaming yourself for someone else's actions, etc.).
