For some reason i can never log in from my ipad. I just got a blank screen. I thought it was the site was always down, but when i tried from my laptop i had no issues. So you may want to try a different computer or a different browser.
Did you try logging in with your romance reward #? I had a problem when I tried logging in with my e-mail address, and I called Couples to get help. They had me log in with my romance reward #, and that has worked for me every time.
For me, when I log-in I have to hit the loigin button, and not just hit enter after entering my login and password. As many others have mentioned, Apple Safari does not seem to work. I use only FireFox and have never had an issue logging in.