Hi gman29, I think if you read enough threads here that you'll find a lot of people find themselves playing the comparison game like you are. So it sounds reasonable that you are having some issues about that. And you are insightful to understand that a lot of your life has passed while involved with your uexBPDgf, so it's natural she fills up a lot of space in your memories.
As far as "replacing" her, that might not be the best way to approach thinking about it. Maybe a pwBPD utilizes replacements as nons tend to be soothing tools for them. If you can find yourself appreciating this new girl for who she is, and she is different by light of the fact we are all unique, then you won't be "replacing" but actually "growing" a new relationship.
When you talk about physical characteristics, it's also not unusual for many people to go for a certain "type" or "look" in partners. So it's normal to date partners who are similar in looks.
While it sounds like it's addressing a totally different aspect, I think utilizing mindfulness can help deal with ruminating. Check these links out:
TOOLS: DBT for Non Borderlines- MindfulnessPracticing mindfulness--how do you do it?
