Adi,

Missing someone whom you had a good experience with is natural.  However dwelling and staying in the past does not serve you.

Meditation on those feelings is a way of getting through them and then gives you the ability to be in the present moment.

What do you have around you now?  Who do you have in your life now?  What do you appreciate today?  What are you grateful for?  Write those things down.  All that helps you to be in the Now.

Mark