Your personal life can influence others for good and for evil.
If you live a rather obviously (to your friends) chaste life, your fellow Catholics (and other Christians) who are trying to live a chaste life will find it easier because they won't feel so alone.
But if you live an openly unchaste life, no matter how much the world just thinks that's normal, your fellow Catholics (and other Christians) who are trying to live a chaste life will find it harder because they will feel increasingly alone. Married people, too.
Even if you get married to your partner in sin, you will be telling other Catholics by your actions that you got away with something, and maybe they could get away with something, too. Or that the only way they will ever be able to hang on to a guy or a girl is to compromise their principles, which just so happen to be in line with God's will as taught by the Church and as is quite obvious in the Scriptures.
Everything we do matters. And incidentally we are at war. In war, the defeated side suffers horribly. Our Christian parents or grandparents lost during the Sexual Revolution, and now we all are paying for it. And the war continues, as faithful Christians in the wedding industry will find out, if they have not found out already.
Once upon a time, I was not so "old-school" on chastity, and I said something super "open-minded" to a woman at work who had lived with her husband a long time before they got married (if they ever did get married), and she was shocked. This woman was a cultural Catholic, rather simple in some ways--actually, she was a lot like Penny on "The Big Bang Theory"--and she apparently looked up to me . She knew she should go to Mass, and she admired me because I did.
"How can you [say that] when you go to Mass?" she demanded, and I felt so ashamed, her words helped me get off the path I was going down.
I hope I told her she was right.