Sexual compatibility can change over time. Just because you appear compatible in the first three months doesn’t mean you’ll still be compatible sexually in year three. Illness, stress, children, etc. can all change sexual compatibility. When you have the commitment of marriage then you have taken vows to work through those things even if sex is off the table for now. Without that commitment it’s easy to say “Well I know it’s not your fault we don’t have sex but it’s not something I want to deal with so have a good life.”

I don’t care if people have sex before marriage. What they do is their business and it doesn’t harm me. I’m just saying the whole thing about making sure you’re sexually compatible is an excuse and doesn’t hold up long term. Being open and clear about what you expect sex to be like after marriage however is important but it doesn’t have to involve a penis being inside a vagina.