I recently wrote a question about the modal должен, explaining that this modal is very hard to me because it has very different meanings.
As my question was deemed too broad and put on hold, I would like to ask a very specific question: How should I interpret Phrases (1)-(4) below? These phrases have no context and have to be interpreted per se, as they are article titles.
(1) Должен ли парень платить за девушку на свидании? (Source)
(2) Почему каждая женщина должна уметь флиртовать: мужской взгляд (Source)
(3) Должен ли Путин уйти? (Source)
(4) Я должна была быть мужчиной (Source)
I am confused as to how I can determine the meaning of должен in the absence of any context. In Phrase (1), does должен mean a necessity for the guy (if he wants to successfully start a romantic relationship) in view of the actual mentality of girls? Or is the phrase about the ideal order of things in terms of fairness? Or is it about a cultural norm? Or some internal urge a normal guy must have? In Phrase (2), does должен mean a necessity for women, a wish of men, advice to women, or an expectation of the author about women's capabilities? In Phrase (3), does должен mean a prediction about the future, advice to Putin, an ethical necessity, or what? And Phrase (4) made me especially puzzled - I should have been a man, I must have been a man, I had to be a man, or what does it mean?
Ideally I would like to see the precise meanings and proper English translations of Phrases (1)-(4) as well as explanations how you determine the meanings of these titles without reading the articles, but any helpful responses are welcome.