My husband's first airline job was with Scenic Airlines in Las Vegas. He was dating a girl who he liked very much, and he really thought was 'the one'. He came home pretty much every week (jumpseats courtesy of America West, thank you very much). The girl decided she couldn't deal with him being gone. She lined up another boyfriend who had a 'real' job, then kicked my dh to the curb. (While it sucked for him at the time, hey, he ended up with me! So it wasn't all bad!) She's a prime example of the kind of girl who can't deal with 'the life'.
Commuting can add hours/days to your work schedule. You have to watch loads & weather constantly. Many people do this and have perfectly happy relationships. The key is to explain to the significant other exactly what to expect. That way when you can't make it home because of cancelled/oversold flights, they understand, and don't get angry or resentful. However, there are people who just need their significant other to be around constantly, and can't deal with being alone, or not being able to call whenever. You will probably date one or more people like this, and hopefully you'll not be hurt too bad by one of them.
Commuting is neither good nor bad. It is just, well, commuting!
I think there have been a few other threads about commuting, do a search here in the forums and you may find out some more info!
ps. Send the significant other to Kristi's great website,
Families of Commercial Airline Pilots.org there's lots of us significant others there who can give advice on dealing with the 'lifestyle'.