To reiterate, if someone from the past has got you feelin' worried, it's important to talk to your partner and get it all out in the open, especially if you're planning on staying together long-term.
The only way to gauge whether or not your partner loved the other person more than you, or if they secretly want to get back together, is to point out the behavior that you interpret to mean that they love their ex more than you, Forshee says, "and then inquire about it to understand from your partner’s perspective what the experience was for them." If your relationship is healthy, and your partner is worth your while, they'll be happy to answer, clear up any confusion, and find ways to be more reassuring going forward.
You can always look for signs of commitment and love, like the ones listed above. But keep in mind that it also falls on you to feel secure in your relationship, and not get caught in the habit of constantly sizing yourself up against whoever your partner dated in the past. By living in the present moment, and appreciating what you have, you'll be doing your partner to move the relationship forward in a healthy way.
Studies Referenced:
Rhoades, Galena, K. (2010). Should I Stay or Sholud I Go? Predicting Dating Relationship Stability from Four Aspects of Commitment. Journal of Family Psychology. 24(5): 543–550. doi: 10.1037/a0021008
Experts:
Dr. Danielle Forshee, clinical psychologist
Racine R. Henry, PhD, LMFT, licensed marriage and family therapist
Jonathan Bennett, certified counselor and relationship expert at Double Trust Dating
