Most men have spontaneous desire while women usually have responsive desire
I think this fact causes more problems in sex life that it needs to. Besides fresh couples, women are less likely to just spontaneously want sex.
It usually requires build-up and is much more responsive. Men can feel undesired after a while and eventually get frustrated about not having enough sex while all it might take is a little tease in the morning.

Love is kind, but not blind
Heard this quote from a women on a podcast that I can't actually remember, but the quote stick for a reason.
There definitely is something about e.g. occassionally dressing up for a date. Not even for the sake of dressing up for your partner, but also for yourself.

30% of couples don't have sex after 2 years of being together
I've been reading a lot about relationships and intimacy lately and this fact stuck me off guard.
Of course, this is not necessarily a bad thing if all parties are happy, but usually it's a sign of disfunctional partnerships.