Am I being silly over a house?

SO and I have been together a few years and have lived together in his house with his children (SDs 7 and 9) for almost two years now. We have 50/50 custody. This house is the house he spent almost ten years with his ex-wife and it never really used to bother me that much especially if I didn't focus on it..but we are expecting our first child together and I'm having a tough time being okay with living in "their" house now for some reason. It never has completely felt like home, so maybe being pregnant is making me resent that more? Am I being silly? It's just a house.. Also I know moving doesn't just effect me, but the girls and their school, friends, distance to their mom's house, etc. Anyone been in this boat before?