widower
The term 'Witwer' is used in German to refer to a man whose spouse has died and who has not remarried. It is the male equivalent of 'Witwe', which is used for a woman in the same situation. This term is used in both formal and informal contexts in German, much like the term 'widower' in English.
I am a widower
This is a simple statement. Here the speaker is declaring their status as a 'Witwer' which is German for 'widower'. This is a common way to refer to a man whose spouse has died.
The widower is mourning his wife
In this example, the widower 'Der Witwer' is subject of sentence and is expressing his feelings of sadness over his wife's death. It provides context about emotional state of a widower.
He is a sad widower
This example showcases an adjective, 'trauriger' meaning 'sad', to describe the state of the widower. This commonly describes a man who is going through a period of mourning.