You cannot realistically start criticising someone else for the breakdown of the relationship before you have looked at yourself. There is no need to be too self-deprecating but really think about whether you are to blame for some things that you may have laid blame on your partner for. Also really think to yourself if you have been the best husband or wife that you can be and whether you can make changes to address this.
It’s time to let go of any idea that you might be clinging on to that you are going to leave your current partner and walk straight into the arms of the man or woman of your dreams. It just doesn’t happen like that. Instead, try and find those attributes you desire in your current partner. The chances are that they are there but you are seeing them in a different way because you have been together for so long. Also think about how you would feel if your partner was to find someone else; if you can’t imagine yourself being ok with that then there are obviously still feeling there.