If Muhammad is really a man of sex, he would not married an old 40 years old lady when he was 25 years old. Don’t you wonder, at the time where the Arabs usually married among them during their young ages and the culture of Arab at that time allow all of the men to marry as much women as they want after that without any restriction, Muhammad did not do all of that. He married a 40 years old lady named Khadijah and even stayed with her for 25 years without marrying any other women during that young age!
Only after Khadijah passed away, Muhammad start to marry other women in an amount of numbers at the same time, and at that time he has already reached the state of an old age (more than 50 years old) which we know for the state of the human at that age normally does not have much desire to woman.
But the West still want to accuse him as an old man of sex due to his action on marrying many women.
Don’t you read the history of the previous generation of humans before that? It is a normal thing for the people of the previous century to marry many women during their time actually. Even the honourable David himself married more than 100 wives as narrated in the Bible. And so do the other honourable men before that. They used to marry more than one woman and it is a normal culture of the life during that time.
Before we go even deeper, one point should be clear. Marriage is not only about love and sex. Although most of the western culture symbolise marriage such as that way, in Islam it is more than that actually. Marriage is not only about love and sex. It is beyond than that.
Muhammad married women during his old age not for the purpose of sex. It is actually for the purposes of many important things during that time. For example, Muhammad once married an honoured woman named Sufiyah. He married her so that all of her great tribes follow her to accept Islam. Another example is when Muhammad married one woman named Zaynab. He married this woman not for the purpose of sex, but for the purpose to legalise certain new legislation in Islam - the rule of marrying wife of adopted son in Islam.
And if you study more about the history of his life, you will found many more. It is only the issue of whether you are really SINCERE want to know about it or not.
Sincerity in studying.