So my girlfriend (K)’s other lover (D) is constantly trying to get her to break up with me, and being emotionally manipulative on the verge of abusive to her. D’s not ok with being poly, but she knew that me and k were together before she got involved. K has already said she doesn’t want a relationship with D because she’s not good for her mental health. It seems so simple to me that she should break contact because their relationship is harmful. But they’re in love so… It’s difficult. Any advice?
You have your picture of what’s going on: D is being abusive, manipulative, and unhealthy for K. But it’s not clear that K shares this perspective. You say that K agrees with you and doesn’t want a relationship with D, but for her own reasons, K has yet to break up with D. That tells me that there’s something else going on. K may be telling you what she thinks you want to hear rather than what she really thinks, or her definition of “in love” may not jive with yours - it’s worth sussing those out through open communication.
This is a really tricky situation, but the thing to remember is that you can’t control another person’s choices, nor can you change their worldview. If your girlfriend has her reasons for staying with her other parter, those reasons are real to her, even if they aren’t apparent or rational from your perspective. If you start pressuring K to leave her other partner before she’s ready, you risk becoming part of the problem. Be an active listener and do your best to find out what K is feeling and needing in this situation. It can be hard, but try to speak into her reality with support and validation rather than trying to drag her into yours.
If it turns out that K really doesn’t want to leave D right now because her definition of “in love” allows for what’s going on between her and D, and that trumps her desire to be free of this toxic relationship, you can’t change that. You can only decide how close to this situation you are willing to be, for your own personal health. If it turns out that K does want to leave D but feels she can’t because of fear, concern, insecurity, or other issues, find out what she needs from you to support her through this, and do your best to make the exit safe and healthy for her. Remember that you have an outsider’s perspective, and what seems obvious to you may be hard for K to see if she has been manipulated.