It will be unhealthy to stay in a relationship where you both ain't happy anymore. There is always someone out there that will want to be with you for you and then eventually have more baby's. My son's father wants the same but I chose to leave and it was the best decision I made, yes I want more kids but if I can't I'm just going to adopt with or without a new partner
You never know what the future holds, but if there’s no love you need to leave before you complicate things further for all involved