Well, I think it is because you are the only one currently who can offer that option for her. Suckling is comforting for your baby. You can consider offering a pacifier in place if you are open to that option.
One of my friends really enjoy these sessions with her daughter as she feels that it is her "cheat" way of soothing her baby. Though it is really tiring but she was able to sleep through the such sessions now.
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