How can members of the zodiac date each other?(may contain spoilers)

well sometime the two r really in love. they feel like they r distantly related when they r under the curse. but when the curse is broken they feel entirely different and happy for each other.

I think somewhere in the manga they say something about the whole 'cousin' thing (I'm not sure where). But I believe they said that their not sure exactly how they are related but since they all have the same last name they must be somehow, hence why they say their 'cousins' (and their bloodlines are so far apart that it doesn't really matter if they date. Remember it's a HUGE family). It's like if you know someone you has the same last name as you but none of your or their relatives know each. And none of them look like each other either. I also don't think they have to date another zodiac member just because of the curse (ex: Yuki and Machi, Kyo and Tohru, Kureno and Arisa, Hatori and Mayako, Ritsu and Mitsuru, Ayame and Mine, the previous cat). Haru and Rin, and Hiro and Kisa are just in love with each other simple as that. Hope this helps! :)