I have a gf that lost her childhood sweetheart to cancer 2 years ago, they were together over 20 years, remarried before he died and had a 2nd honeymoon. they also have two children together. She is still young in her mid 40's and within a year she was dating again and now living with another man very similar to her husband.
She simply just couldn't be alone...it's been rough and she has had a lot of people putting in their 2 cents worth including her children but she has chosen to live her life the way she wants. The man that she is with is a lovely guy and he takes back seat still to the husband as he lives in their home with the 2nd full sized wedding picture displayed in the living room, associates with their friends that are always remembering him and even has his ashes in the same room that they sleep in!!
She just simply cant be on her own, some people are like that... she is very happy and has something to live for again?
I on the other hand lost the person that I thought I would spend the rest of my life with...although I have moved on and had other partners, I have not stayed with anyone for any length of time and I'm doubtful that I will find someone again. I don't need someone to make me feel whole, if they should come around I hope that I aren't too closed off to recognise him.
It really comes down to the person in question, some people just have to have someone and others are quite happy and alright on their own. In my world, of the people I know that have lost to death it's a 50/50 thing as to whether they have moved on or stayed single and waited for their loved ones.