i'm almost at the end of the main story arc (i think^^) and i still haven't got his perk

i got so many "Danse loved that & liked that" from entering my PA or modding weapons, but still no more private conversations...

when did you get his perk? i mean it didn't take very long to get cosworth's, piper's and valentine's perks...

You have to complete the quest "Blind Betrayal" in order to max his character out.

Keep doing the main storyline. Specifically, you'll want to do BoS related storyline missions. Be careful though if you don't plan on sticking with the BoS. If you get to the Mass Fusion quest handed out by the Institute and want to complete a BoS quest involving Proctor Ingram before getting Blind Betrayal, you'll be forced to do Mass Fusion (in a sense. It'll make sense later) before finishing the BoS quest, if you completed the objective "Talk to Allie Filmore". How you do Mass Fusion results in either the Institute or the BoS being hostile towards you. So in other words, you'll be forced to do Mass Fusion in favor of the BoS if you want Danse's perk. To prevent this, either don't talk to Allie Filmore after you have been handed the Mass Fusion quest or complete BoS-related storyline quests first. Then there should be no conflict and you're able to get "Blind Betrayal" and Danse's perk while free to still choose your faction.