Hi, skittles. My opinion is that it could be a "sign" but I guess it would depend more on how your boyfriend sees it since it was he asking God what to do. Doesn't help to pre-empt someone else's questions with answers we want or believe? :-)

If I were in your shoes I would start a conversation with your boyfriend, talk about what sort of response he was anticipating and how you see/want it and reassure him you don't want to "break up" (if you don't :-) and how his wanting to look at the apartment worried you.

I don't think God is limited in how he responds to our prayers but tailors his responses to us and to our ability to read them. I generally don't have to wonder when I get a response, even when I'm being "thick" because then He generally sends a lightning bolt kind of resonse so I "get it" :-) if I'm being too dense. Maybe your boyfriend got another response he didn't tell you about or sees the already rented apartment the same as you. Ask him!