I have suffered a few major losses in life and have ALWAYS taken them very hard. Even losing a pet would send me into a spiral of depression so you can imagine some of the things that I have dealt with when losing someone whom I cared about very much. My great uncle was so bad that I couldn't even shed tears until months later, it was pure shock. Losing my son at 9 days old gave me nightmares for months and watching shows with children, especially babies, where they are in a life or death situation is a big trigger for me. Losing my wife was the single hardest thing I have ever dealt with and the only thing that kept me going was a promise I made to my wife...
I still refer to my son as my son, NOTHING will change that. EVER. I still also refer to my wife as my wife most of the time. Her first name is Shaunamarie and I would often just call her Shauna but when I talk about her many time I just talk about my wife. My girlfriend has been ok with it and the other day I actually asked her if it bothered her because I have started to notice this and I don't want her to feel like she is second fiddle to my wife. She understands and we talk about things like this as often as possible so there is no animosity about things.
If you are dating someone who has lost a loved one. Understand that if they start talking about their wife or husband or partner or whatever it does not mean that they care about you less. It means they are trying to heal and still remember that person as well. They are not doing it to cause you pain and please DON'T take it that way. If it bothers you mention it when they are having a good day, be calm, be willing to talk about it. Don't give them an ultimatum about using the term unless you are ready to no longer be around them ever again. Losing a loved one like a wife or husband whom have been a part of a persons life for many years is tough to do and it's NOTHING like a divorce where you have pain and often times animosity. And the hardest losses to take are the ones that are pretty much unexpected, losing someone to an illness that has taken a while to progress knowing that things are going to come to an end around a certain time are in some ways easier to deal with because you can tell that person goodbye. I woke up one morning to find my wife not breathing and it was not exactly unknown that she was sick but it was not expected to happen for years down the road.
Please take the time to care for the person you are with and enjoy the good things as often as possible. When you help heal a person with a broken heart you will get cut and have some pain as well but the person you help will be the most loyal person you can ever have in your life.
Stay safe, don't be stupid, enjoy life, and Do Good Things.