Saurreg, I think I can answer that.
Elf Women are beautiful, more than mortals. Remember the nature of Elves as the fairest?
Elf Men are too proud of themselves(they think they're really cute)to marry mortal maidens.
No mortal was as beautiful as an elf maid save Morwen of the House of Beor.
No elf bothered to court those mortals.
And they didn't want a wife who would eventually die while they live forever.
that is unless they're slain....
Mortal men had guts to court elf maids coz they don't have much pride.
Some of them think that mortals are just, you know, second to the fairest ....
Beren, I think, knew Luthien as fairest since he didn't get a chance to see Idril, Galadriel,etc
And as for Aragorn, I think if Arwen was not Elrond's daughter[let's say Thranduil's] he wouldn't dare. Arwen was part mortal, right?