Its always a good idea to check in with your partner. After all, you are part of a team, they're not just some furniture that comes with the house (and what if your couch started doing something it didn't usually do? You'd definitely check on that, right?). But I wouldn't necessarily put "just" before "depressed". I'm sure you didn't mean it but it kinda comes off like, "Oh no, are you gonna leave me?! Oh, you're just depressed, no worries then. Just so long as my status quo's not affected." I've been in situations where my partner was refusing to get help for mental problems and the only way to push them towards getting help was for the relationship to end (they needed the change to motivate them and allow them to focus). I've also left relationships because I was depressed and not getting any support and being expected to continue my half of things with no help was dragging me down further. Sometimes both things happened at once. Either situation sucks for everyone involved but it was the right thing to happen.