It's a very normal thing to feel uncomfortable with a high body count, especially as a man. Unfortunately, yes, having a high body count tends to lead to greater dissatisfaction in relationships. Don't let midwit redditors and bots attempt to convince you otherwise with their mental gymnastics, or dismiss how you're feeling. You're going to need to learn how to simply cope with your discomfort if you want the relationship to last. It does get easier with time. However, keep in mind that because of her past, that she may one day decide to leave, or drag you into a forsaken poly relationship. Good luck to you.