Difficult Vs. Challenging
What is the difference between the words difficult and challenging?
Webster's Dictionary defines "Difficult" as something hard to deal with, manage or overcome. It defines "Challenging" as testing one's abilities.
My interpretation of this is that something challenging can reap a reward such as a having a healthy, happy, peaceful, easy relationship with your partner (or with yourself) when you take the time to set a sturdy foundation that allows you to plant deep and strong roots.
Life and love can and WILL present "challenges" to make you grow and change you into something better. Whether or not those challenges are "difficult" depend on the perspective and mindset you decide to live in.