Falling in love doesn't necessarily need closure in order to happen. But loss of closure could be distracting you from finding the right person. If things are still eating away at you, love is the last thing on your mind. Falling in love may seem distant, like a fantasy. What you need is to come to terms with what's really bothering you. Your emotions are important, so it's up to you to protect yourself from further emotional pain in the future. Take some time to think about why you can't fall in love, assess your feelings. Only you know the answer to this question. All I can do is point you in the right direction.
And by the way I am truly sorry for your loss. I wish you the best of luck.