Ummm...it takes two to make it work, not just him. And she may not have been as into it as him.
In answer to the OP's question - I'm guessing that the problem is that, whatever you are doing...you are still thinking of her even as you are doing those other things.
This is unhealthy for you on two fronts :
- it keeps you longing for her, not allowing you to heal
- it's rendering everything you do washed out, grey, dull, and probably meaningless
In other words, it's keeping you from putting your heart into other things, and keeping you from finding meaning in these other things.
She was a treasured part of your life, and you will always have memories, but it's time for you to let go, and give the other activities in your life the attention they deserve...to allow them to have meaning in your life...which will allow them to be more treasured, and which in turn will lead to you thinking of her less, and less.
Or, in another way - when you do an activity, put your focus into that activity...consciously choose to not think of her, and then give your focus and attention to what you are doing - be in the moment with what you are doing - put your heart & soul and focus into what you are doing...
...you will find that life improves.
..then start finding your passions.
A grounded & passionate life is never an unhappy life. Find your grounding, and find your passions