You might see your partner and yourself through the lens of many assumptions.  Then you begin to act toward your partner in ways that confirm these assumptions.  Instead of changing your assumptions, you become disillusioned that love is not what you thought it should be.

This episode is also available as a blog post: https://lovelifeprof.com/2017/09/19/assumptions-that-cause-disillusionment/ 

Find my book, Love Demystified: Strategies for a Successful Love Life at https://amzn.to/398rk93 and follow me on all social media @LoveLifeProf