I didn't think it was too difficult coming back to my chapter after six months in Australia. I was initiated in March and left in July for Australia, so I didn't have a long time with my chapter ahead of time. I kept up with sisters through email and IM (we were lucky and could have computers in our rooms). I also got all the chapter emails about what was happening, so I kept up that way. It was a bit sad missing out on a lot of the Greek traditions and parties and sisterhood that semester, but I hung out with a lot of Greeks in Australia.
I know some of the people from my school were very homesick to get back to their sisters at school and therefore spent a lot of time talking to them and hurrying to get home rather than exploring the country. They now regret not taking full advantage of their time there. I guess my advice is to make sure you do everything you want to do while you are abroad and don't spend a lot of time being homesick for your sisters/family/etc. You'll regret it later if you don't do a lot.
To answer the other part of your question, I left behind my boyfriend of 5 1/2 years at the time. I was very upset to leave him, but we talked on the phone twice a week. He understood that I didn't have lots of time/money to call home every day, and he knew I wanted to do a lot in Australia. I extended my stay by 7 weeks. I was upset about not seeing him, but I had such an amazing time that I really wasn't too sad. I knew I would be seeing him when I got back, but I didn't know when I would be back in Australia again. I wrote him a lot and he sent me packages.
Good luck with your study abroad

I know it will be one of the best experiences of your life.
--Sharon