The guy is probably dating other women. Why shouldn’t the woman?
What makes you say that? Most guys, especially moderately to very successful ones, don't have time to date around, even if they wanted to do so. First two-three months I'd agree with keeping it non-exclusive, but there is zero chance I'd ever have committed to marrying a woman who hasn't shown she can commit pre-marriage (been married for nearly 12 years so mute point at this point, but my wife and I went exclusive dating after 2 months and I proposed a bit after a year)
Why would you assume that?