There’re several situations and reasons that can easily drag anyone into it. This is regardless of your marital status and the level of your religious commitment. The more you associate yourself with these factors, the easier it is for you to fall to the trap of zina.

Here, I’m not specifically indicating any cause that could lead one to it. I’m rather saying, any activity, situation or interaction that provokes your sexual desires can lead to zina. Unless the person involved is your legal spouse, it’s necessary to take preventive measures in such situations. That’s if you can’t avoid such situations altogether.

For instance, delaying marriage where one’s urge for sex is strong could lead him or her to it. Also, if you are easily attracted to the opposite gender (and who is not?), then you should minimize your interactions with them, unless there’s a need. And when you have to, and must interact with the opposite gender, it should be in the open; in a professional setting. One should try as much as possible to ensure the presence of a third party. Just not only the two of you in a secluded place!
If you live in the Internet (and you know what it means to live in the internet. Don’t you?), then be cautious of your usage of social media. Let your use for Facebook, Twitter and Instagram be for good. Do not allow them to lead you to pornography which leads to it or the secret habit. Similarly, movies, dramas and some media materials can be damaging to the modesty of the Muslim, in many ways that could lead him or her to zina.

The Qur’an explicitly indicates that it is immoral and an evil way. It is such dangerous that, the Qur’an doesn’t only command us to refrain from it. In fact, it warns us from getting near to it, in any manner. This is what is understood in the verse of Sūrah al-Isrā’, 17:32:

“And do not even approach zina, for it is an outrageous act, and an evil way…’’

Marriage wont stop it

A dog will always be a dog. Marrying 70 wives or husbands cannot stop zina.