<human>: Could you distill the essence of the text into 1-3 sentences?

There are many variables in my current relationship that are novel to me and my partner. Our age gap is the most obvious, followed closely by the fact that he has already gone through a divorce, has two boys ages 8 and 10 from his previous marriage, and that I am child free and have never dated anyone with children.

Despite these differences, I have found our relationship very fulfilling, and he is very loving and voices his appreciation in having me around. 

I met his kids about four months in and was introduced as his friend. We have moved from my seeing them very sporadically to seeing them once a week when they come to his place- although we have both been conscience about making sure they have alone time with him too. They seem to like me. They tell me stories, and I recently started reading them a book of poems from my childhood. We play games I bring over and have had a few dinner and dessert cooking nights. In short, I think they are the bee's knees- even when they bicker between each other or get picky with their food. 

It has become obvious that I am not going anywhere anytime soon. I love this man and adore his children. We are talking about my meeting his ex-wife so that she at least knows me and my intentions. My worry is that I don't want these boys to think I am trying to replace their mom. 

Last night the youngest one was getting nervous while we were all watching a detective show. (He is very sensitive to scary music). My gut told me to reach over and cuddle him, but I stopped myself- thinking I was overstepping some boundary. Instead, I switched places on the couch with his dad and encouraged him to give the 8 year-old some reassurance.

How do I tread that line between acting as a loving, stable adult presence in these kids' lives and not stepping on their birth mother's toes?
<bot>: My partner has kids. I never have. I care about them all and don't want to come off as trying to replace their mom.