Over the years, I have had two long term SB/SD type relationships "end" the way you describe, only to have them contact me about a year later and ask to pick up where we left off.

 
Stay subtly in touch like sending a brief text on her birthday, or some occasion like Christmas, nothing heavy, just a brief hello, how are you?  

 
The art of being a good "breaker-upper" can't be over-stated.

That's an impressive young lady.  The vast majority of women I've met would not be classy enough to handle things the way she did.  They'd just ghost you... or lie to you... and be undisturbed about it.

I saw a sugar babe once.  After we were pondering our next meeting when she said she just got a new boyfriend and she would have to stop seeing me.  Literally two days later she contacted me and said we could meet again -- which we did.  

I've had quite a few SBs who went through several boyfriends during the time we were sugar dating.  The coolest girls were open with me and with their BFs about seeing other men.  Being ENM was the condition their BFs had to agree to in order to be with them.  More commonly, they never told their BFs about my presence in their lives and we kept dating secretly.  And of course, a few just ended it with me when a new BF entered the picture, sometimes elegantly like Netnoy described, more often simply ghosted, which I hate. But I totally agree, don't burn bridges!  You never know when a past SB is going to urn up again.  Matter of fact, I've got one of those in the works rn.  We dated regularly back in 2019.  She has a solid, live in BF who knows about me and is evidently cool with it.  And she wants to get together again!