My take on this: subtly hinting is a difficult thing to get right in this situation, mainly because you will be working in a verbal medium where you will literally have to spell out what the character feels. It sounds like what you want is to add foreshadowing, so the reader thinks 'oh yeah, that makes sense now!' That would be a challenge in this particular situation, but maybe I can offer you some food for thought.
To illustrate what I mean when I call it a challenge, here's a little example (and I'm just going to go with a young man as the character here for the purposes of my example, even though you don't specify): imagine you try to hint about a character's feelings by having them say 'When I turned around and saw that John had come to the party too, my stomach seemed to fill with butterflies – happy butterflies.' (I didn't claim that this was going to be a particularly good example…) Or 'John wasn't really my friend, but I always felt really drawn to him'.
In real life, a person may not immediately equate 'happy butterfly feelings' with 'I have a crush on this person' because our feelings (and stomachs) do inexplicable things all the time. To a real person, the happy-butterfly sensation could, for example, go mostly unnoticed in a wave of other things they're feeling (maybe they're a bit nervous about the party anyway because they know an enemy of theirs will be there, maybe they're excited because they managed to sneak out of the house without their parents noticing, maybe they're feeling unwell after a dodgy kebab), or they might interpret their feelings as simply being glad to see a familiar face, particularly if they're not enjoying the party.
But because you have to verbalise it, the meaning of these happy butterflies is blindingly obvious to the reader, who may very well consider your character clueless for not getting that same meaning - unless you mislead the reader into suspecting another logical reason for the character's reactions/emotions.
How to mislead the reader? Here are some ideas. Maybe when the character's friends (again, let's pretend the character is a young man) start talking about how hot some girl is, or about their various fantasies, the protagonist gets bored and wanders off. He just feels this conversation isn't really for him. He has no enthusiasm for the topic. 'The guys were boring the crap out of me – couldn't they just give the freaking Cindy thing a rest? It's not like there weren't plenty of other things they could talk about.'
If there are other things going on in the story, the reader could well believe that the character is simply too preoccupied with those events to be interested in trivial matters, for example.
Or maybe you could indeed use the 'happy butterflies' feeling, but the protagonist thinks they're happy for some reason other than having a crush on John (e.g. because they thought John was dead and were freaked out about it, or because they know John has the cure for the super-cancer that they have desperately been searching for (yes, I checked out your other question!)).
That type of approach could 'hide' the protagonist's feelings from both him/herself and the reader, making the 'reveal' work as an 'Oh yeah, of course!' moment.