Long-term relationships in the hobby can get tricky. Optimistically, as familiarity and comfort grows over time, real friendships can develop and nudging of boundaries can naturally occur. You can also characterize this as a long time customer expecting special favors for his loyalty. But, simply put, he wants more than you're willing to give and you told him so. A slap on the wrist may make him back off for a period, but he'll be back at it at some point.  

This will only end when YOU end it. I'm crossing my fingers that he won't give you a hard time with the "break up."

Sometimes they need to end.   I need a level of comfort with my partner.  If the terms of the relationship have changed to where I feel uncomfortable with him, I'll voice my concerns and have terminated partnerships.  Lesson learned: A bitter Lea is not sexy.

after a hobbiest has spent literally thousands on a single provider he grows weary of merely a physical connection. Some hobbyists will simply 'move on' seeking a new experience, others may seek to move the arrangement to a higher level for reasons of perceived entitlement. Often a provider may subtly or overtly 'lead the hobbyist on' consciously for business reasons, or inadvertently/innocently not knowing better.    

  Providers sometimes delude themselves into wanting a higher level in the "arrangement" and too succumb to wanting or affording inappropriate "favors" and possibly stalking of the hobbyist.  

The penis as well as the pussy is hardwired to our ego. The money factor is largely the culprit overlooked or conveniently denied in the common blurring of etiquette and expectation lines in the hobby. Forgetting this by either party has historically proved problematic.