childless step-mom success stories, please. what does that look like for you?

i know everyone’s situation is different and so many posts i read are doom and gloom and that it only gets worse and not better. does anyone have any happy outcomes? healthy relationships with their partner and the kid[s]? if so, what boundaries do you have in place? what responsibilities do you take on or not take on? how much time do you take to yourself? i believe in being honest and transparent with my partner always. i came into this family where my partner has 50/50 custody of his young children. i am child-free and i am hesitant to bring more children into this world. i wish i reacted to children the way i reacted to dogs… “oh my sweet baby! come here! let me hold you!” but that doesn’t come naturally to me when it comes to kids. i know i can’t force or change my inner callings. i was never passionate about motherhood; but it doesn’t mean i don’t care for the children nor will i ever ignore their existence. it is important to me that they feel supported. i love my partner and i want to be there for him (without ignoring my needs or losing myself). love is boundaries and i would like to hear what are yours.