I think a great place to start at, is with the question focused to “what qualities/personality/behaviors does this person have that remind you of another?”
The desire to be with someone because he/she reminds you of someone else can lead to a negative place. You may find yourself internally in pain as well as hurting in the relationship. Always lusting and seeking something that isn’t present.
On the other hand, the basis of positive and negative, is dependent on what about the person reminds you of someone else. With the question being asked, try to focus on the behaviors of the other person that you are reminded of.
Let’s say that the behavior is that of “kindness”. This is a behavior that in essence, is positive and can be mirrored.
One of my favorite books is the 5 love languages. It focuses on helping people understand their love language and overall how one accepts and provides love. If you are with someone because he/she reminds you of the behaviors of someone else, then work together to build a strong relationship by focusing on what can build the relationship. One that meets the mutual needs of the relationship.
Using the example, above “kindness”. It may be of benefit to discuss with your partner that you find “acts of kindness” attractive in a person. Your partner may, if he/she, desires to transition to the positive behavior of engaging in acts of kindness. Engaging in acts like (a) spending time at charities (b) volunteering (c) cleaning your car or home (d) writing a letter of appreciation.
Overall, I think that the question being asked should be further evaluated and understood as it impacts you, your partner and the future of the relationship.
With Love Juan Santos M.S., CRC, LPC