I again am probably in the minority here but I personally believe that a couple must have a good and healthy sex life first before marriage.
There are just many things that opens up after sex. So many questions answered and so many what-ifs and unknowns known. And idk if it's just me but being compatible with your partner is really important in a relationship. It's not really about lust but more like the satisfaction you could get from your partner. Sex is on top of Maslow's psychological hierarchy of needs for a reason. Because it's important.
The simple act of having sex also allows the two to know each other more. So it might be healthy physically (you both are sure clean from any diseases) but it doesn't mean it will be healthy to the relationship.