I think Marrily.com has a much better brand quality than marri.ly does. It's easier to pronounce too, marrily-dot-com (and you can also type marryly.com and get redirected to the main site) than to pronounce "marr[i|y]-dot-ly". People will probably get hung up at the i in the word "marri", since there can be 2 different spellings: marri or marry.

Too bad I couldn't register "merrily" (and its variation: merryly). Merrily was the first name I picked but it was registered to a lady in Seatle. But Marrily does it for me too, plus it has a nice twist to the name (to marrily means to marry happily).