I wouldn't say there is anything wrong with it at all. Everyone needs time to themselves, just because you have a family doesn't change that. I finish work around midnight and I enjoy being able to come home and do my own thing for a couple of hours before going to sleep.
It's essential to have 'me time' in a relationship, not having so risks co-dependency (or symptoms thereof). What OP is describing seems very healthy to me, as does your comment (:
Unfortunately, even if both in the relationship have “me” time, codependency can still be a likely possibility.
I think to avoid codependency one must truly be able to enjoy one’s own company no matter the circumstances, or have a very active and fulfilling social life outside of the relationship.
Codependency is not a real thing. The whole idea pathologizes a normal human tendency, which is to want to be close to people we love or care about. There are different styles of attachment-- some healthier than others-- but humans will always need other humans, and there's nothing wrong with that.
Normally I wouldn't say anything about it but the concept of codependency really only serves to make people feel ashamed or guilty that they "need" someone else other than themselves. Of course they need other people. That's how people survive.