He was really awkward looking as a kid. And he never grows out of having that mind image of himself.
Sure he flirts all the time and people respond, but he figures they’re just being nice people who put up with his looks, are really horny and any body will do, or are teasing him (for good or for bad depending who’s doing it). The jokes about him being the posterboy for the resistance (and how they'd get more recruits if they put him on an actual poster) make him really uncomfortable, because why would he be?
Cue Finn (and Rey) trying to let him know they find him really hot and him thinking they’re just trying to be nice, feeling really awkward about it all and wishing they’d just stop already.
Pre-relationship or established, go with what grabs you.
Finn/Poe or Finn/Poe/Rey - Poe doesn’t actually get how hot he looks.
Sure he flirts all the time and people respond, but he figures they’re just being nice people who put up with his looks, are really horny and any body will do, or are teasing him (for good or for bad depending who’s doing it). The jokes about him being the posterboy for the resistance (and how they'd get more recruits if they put him on an actual poster) make him really uncomfortable, because why would he be?
Cue Finn (and Rey) trying to let him know they find him really hot and him thinking they’re just trying to be nice, feeling really awkward about it all and wishing they’d just stop already.
Pre-relationship or established, go with what grabs you.