Okay, we've gone a little off topic but I'll answer anyway.
This would be true if you assume sexual compatibility stays the same as when you are first together. And I would also say sexual compatibility is only one aspect of how relationships survive and are strong.
Sexual compatibility does stay the same what changes is maybe how often or trying new things. I think you maybe referring to a marraige where the sex stops for whatever reason. That doesn't mean you are not compatible anymore just means that for whatever reason one of the partners has lost interest and if you have any interest in saving your marraige you'll find out why and fix it.
What if your partner make some weird noise during sex or just does things that irritates you to no end?
Oh yeah things can cool off but it's up to the couple to keep it interesting and try new thing to keep it spicy. Now if you marry someone and don't test drive how do you know if that person has an interest in trying new things or keeping the spice in the relationship? Maybe that person wants to only do missionary position and you just can have an orgasm in the missionary position what then. If you find out after the fact this person is a total dud or can't even get it up then it's too late.
Sex is one aspect but it is a very BIG aspect to having a happy marraige. I've been married to my husband for almost 22 years and we've had our share of problems, but sex was never one of them!
nj