Hi Tilly and thanks for writing to JA
I am sorry to hear about your situation. That said, I have seen the same exact scenario many times over. As soon as the time approached when you were willing to make a significant change in your status as goes your relationship with your lover, he got cold feet and backed off your agreement. This is quite common indeed especially in long term arrangements such as yours.
You see in some ways your lover has had the best of both worlds. You were there for him for the "fun" parts of an intimate relationship and yet not the "messy" parts that we all commit to when we engage in a more committed relationship. Were this dynamic to change there would be more demands on him to engage with you in matters that are not as easy and enjoyable as that you have shared over the past eight years.
Without knowing you both and knowing much more detail about you, your marriage and your lover and his life it would be impossible for any of us here to advise you in any appropriate way. Since you are considering making such a drastic change in your life have you considered seeing a therapist for some brief treatment to help on this?
Let me know what you think and how I can best help you further on this?
You know I can only tell you what I have learned from over thirty years experience in this type of situation.
Certainly since I do not know you or him I cannot say for sure that what you are reporting is not what happened at least on the face of things, but I am not convinced of what you are saying. Yes I am sure it does seem as if it were he who had the best of both worlds and that he begged you to leave your husband, but then again, he left before the deadline.
I am pretty sure that in many situations in life things are not as they seem. I think he is telling you that he left because he could not take the pain anymore. However, this does not, as an impartial observer ring true for me. I think he is telling you this to make you feel bad. That said, I would be hard pressed, were I he, to understand why your daughter's birthday could not have been celebrated at another time so you could have attended the wedding with him?
You see if you were not able to rearrange the celebration for your daughters birthday to accompany him on a very important family function then he might very well have decided enough is enough.
I think there is more to this situation and I am not sure it can fully be explored in a forum like JustAnswer, but I would more likely lean to 1: He was not as invested as he "seemed" to be or 2: He took your unwillingness to accommodate his plans for his brothers wedding as the last straw. He might have thought that if you were unwilling to make a simple schedule change for him your future together was not as bright as he had previously thought.
Now whatever the reason the outcome is as it is, I do know one thing for certain. That is that people do exactly what they wish to do no matter what they might say otherwise. Often times people do not mean what they say and rarely do they say what they mean.
I caution you that this sounds like a very unstable situation, no matter how compatible you might be and that once free of your marriage you are very likely to find a very different dynamic operating than you have for all the years you were involved with him outside of your marriage. Be careful on this.
Warm wishes and best regards XXXXX XXXXX I hope it all works out.