Where in the bible does it say that we can't have a boyfriend/girlfriend?

I asked someone this a couple sundays ago, and his answer didn’t satisfy the question, so to speak, because it only left me with more questions. Here’s the question: How can we find a husband/wife if we don’t first know them as a boyfriend/girlfriend first?
He told me that the people in the bible days( i know, bible days?) didn’t really know each other then and i said yeah that’s because they were set up by their families and we don’t do that anymore.
He then told me that our goal wasn’t to find a boyfriend, it was to find a husband and the father of my children. He said that you love your husband, and you have feelings for your boyfriend. He said that love wasn’t a feeling, it’s an action, but love is a feeling. Love is a feeling that causes you to do things. The definition of love is to express affectionate feelings for a certain person. I then asked him: Well, if we never have a boyfriend, how are we supposed to find your husband, and how do you know if you will like him in the sort of… romantic sense. He also told me that you could have like, 10 boyfriends, but you could only have one husband. That’s true, but marriage has never stopped some people from cheating on their spouse. So, is it more of a premarital sex thing? And from that we made up our own rule where we can’t have boyfriends or girlfriends, or does the bible actually say something on it?
No, i’ve never done…it. and i’m not doing it till marriage

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