I really need some advice here. I posted this discussion a couple of days ago here for for this topic: http://forums.ivillage.com/t5/The-Challenges-of-Bipolar/Bipolar-or-just-her/m-p/119746183/message-ui... 
Well, for those of you who might not have read the topic it was about a friend of mine and my husbands who has a bipolar girlfriend that seemed to go off all the time. Well my friend was just over the other night and he informs me that he is looking for a new girlfriend because he couldn't handle his current girlfriend since she needed so much care because of being bipolar. Well, it was kind of sad, but in the end if he can't be there for her better to let her find someone who can. However, then he tells me that he is trying to date another girl he met at work and who seems interested in him because she already gave him her contacts. However, he hasn't even broke up with his first girlfriend yet. Instead he plans to go out with this new girl on the side and see how it goes and if it looks like everything is working out then he is planning on just dumping his current girlfriend. I was deeply troubled by this, especially when she called him while we were all hanging out and he told her before he hung up that he loved her.
I don't want to meddle, but this just seems wrong. Sure, she puts him through a lot but to do this to her. I'm worried that stringing her along then dumping her so hasrshly will really do damage to her since she is bipolar and prone to depression. I can totally understand why he is going to leave her, but why not do it properly instead of out of the blue? Getting dumped sucks and I know that no matter how he does it she will be sad, but at least she won't be being used and cheated on in the meantime.
So what do you guys think? I really want to say something to him but not sure if it's my place to do so. Also, he plans to ask the new girl to go to an event with my husband and I and wants us to not mention his current girlfriend because she doesn't know he is in a relationship. So, he is lying to her as well. Any advice would be really appreciated.