Greetings @ebony6!
While I’m sorry your spell didn’t go as you hoped, I can see you’ve got some great advice and suggestions here. There are many possible reasons why a spell doesn’t yield results and in my personal experience, the most common reason is that it simply hasn’t had time to manifest yet.
Some spells work very fast, but I’ve found that the larger and more things that a spell involves, the more time it takes to grow. It’s like a seed- you don’t plant it, wait five minutes, and then come back and expect to find a tree. The more complex the wish, the longer amount of time (and potentially energy) it will likely need to manifest 
Mary said it really well:
This is really beautifully said 
I agree that the more action we take, the more likely our wish will manifest. I don’t see extra work and action as counter or even seperate to the spell, but instead as helping to hone our intention and really pushing it forward into the Universe.
In addition to spells dealing with our own personal situations needing time (and sometime additional work and efforts!), things become significantly more complex when trying to change or alter the situation of someone else (Note that some consider love spells to be against the Wiccan Rede or the ethics of magickal consent , but I personally see them as a grey area of magick depending on how they are being used).
Putting protective measures in place is a very common practice that we use all the time in spellwork and while casting- so of course, when casting on others, we must consider the possibility that others also have protective measures in place that would block or deflect spellwork meant to change them 
Whether your ex is a witch or not, there are all kinds of protective measures and things that could block an unwanted spell or an attempt to alter their situation- even one made with good intentions at heart.
These are just a few thoughts about why the spell didn’t/hasn’t yet worked- to get the best insight possible about your spell and possible guidance on what to do next, I strongly recommend using divination- choose your favorite method and see what answers and advice you can find through your guides/deities/the Universe/etc! 
Good luck and blessed be! 