Hi - thanks for asking the question, you must be a courageous woman.
I live with my DH and DSD14. He and exP get on well - not toxic. Some Disneying and other normal marital challenges but we're getting there. V early days - almost a year married and 3 together. I was a DSD and DH was DSS too. And there's my mum and DH's dad who were also both DSCs - so we have stepping through the generations.
For us our faith is quite important and how we came together was pretty miraculous. We also went on 2 marriage prep courses, saw some wiser couples for mentoring and read books / watched DVDs about step parenting specifically. That's when the shock set in, but to be fair the worse case scenarios haven't happened to us yet, hopefully they won't either.
I love family life and am more long term passionate, than short term excited about marriage, kids etc. So I believe in thick skin tender heart (easy to say, not always to do). I also try to remain positive and most of my posts on MN reflect that attitude hopefully. We've recently also put protected time in the diary every week to talk about whatever's on our hearts, which helps relieve pressures and helps us connect / communicate.
With all that said, would I recommend planning to settle down with a married man? Sorry no. And I was reasonably happy step child myself, yet hand on heart would struggle to recommend step family life. I wouldn't change anything now, love DH and DSD etc. But I had to ask myself the serious question before we set a wedding date "If nothing changed, could I be with this man?". That took about a week of soul searching.
There are numerous benefits: you learn about sharing, you're forced not to take yourself too seriously, you can help bring influence and stability to the home, DSCs do feel fond of their step parent in the main too over time, you learn to give and receive different types of love, you witness kids growing up. But all this is true in first families too once kids come along.
Marriages / partnerships struggle with all sorts, but for step families struggles can be more acute and unique for each member. Grief / heartbreak / feeling neglected is not uncommon for child(ren) especially and SP.
You did ask. Just keeping it real.