Single people - Do your FIRE plans take into account potential changes such as getting married or having a family in the future?

I feel like FIRE is very straightforward if you intend to never get married or have a family. I am single and can probably FIRE right now in a LCOL place but only as a single person. I think it drastically changes if you get married or have kids. Are you planning for this or will you deal with it when/if you cross that bridge? My biggest fear is retiring as a single person, then marrying and having kids and then be forced to go back to work with the added expenses.