Rails InvalidForeignKey

I am developing a portfolio for my website, I decided to add skills to each portfolio item.

class PortfolioSkill < ApplicationRecord
  belongs_to :portfolio
  belongs_to :skill
end

class Portfolio < ApplicationRecord

  has_many :portfolio_skills
  has_many :skills, through: :portfolio_skills


  def all_tags=(names)
    self.skills = names.split(",").map do |name|
      Skill.where(name: name.strip).first_or_create!
  end
end

 def all_tags
  self.skills.map(&:name).join(", ")
 end

 def remove_skill_tags
    PortfolioSkill.where(portfolio_id: id).destroy_all
 end


end



 create_table "portfolio_skills", force: :cascade do |t|
     t.integer "portfolio_id"
     t.integer "skill_id"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
     t.index ["portfolio_id"], name:     "index_portfolio_skills_on_portfolio_id"
     t.index ["skill_id"], name: "index_portfolio_skills_on_skill_id"
  end

create_table "portfolios", force: :cascade do |t|
    t.string "name"
    t.string "client"
    t.date "completed"
    t.text "about"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.string "long_landscape"
    t.string "cover"
    t.integer "category_id"
    t.index ["category_id"], name: "index_portfolios_on_category_id"
  end

When I click destroy on the index page I get the

SQLite3::ConstraintException: FOREIGN KEY constraint failed: DELETE FROM "portfolios" WHERE "portfolios"."id" = ?

error. All the associations look right. I used this same pattern for my tags on other models and it worked with no issues. Any help would be great.