It sounds to me that you have a mature experience and relationship to what it means to Love.  Hating someone who can’t be the person you want him to be would most likely be the ego demanding it could control what it can’t.

Its understandable that your disappointed even angry as you mourn the end of a relationship. In my opinion Hate is not necessary to experience disappointment and mourn the end of something that mattered to you not to mention the imagine future that will no longer be.   That said as Elizabeth noted all emotional reactions/responses are valid.  A contemplative practice would be to feel what you feel and allow them to flow.

The TV show 911 had a story line that dealt with this situation.  I liked how the writers worked through the issue which felt authentic to me. Anger, disappointment,  distance followed by a kind of reconciliation that leads to a extended family. It shows that it could be done when those involved allow what they are feeling to flow and not block them.  In that case the couple involved had children so creating and accepting the situation made sense. The path to accepting involved,  tears, anger and a lot of tough conversations. The key I think was maintaining a safe space to have those conversations.

I was reminded of a quote by Kierkegaard – “The most painful state of being is remembering the future, particularly the one you’ll never have.”
I suspect this is where many people get stuck, unable or willing to let go of what they imagined the future might have been… If Only… and that they often hide that disappointment behind a emotion like Hate. So my feeling is that you are in a good place to feel what you feel and move forward. I wish you well.