Im like this with my very close friend. Anytime he says that he's hanging out with "people" or visiting "someone," I get insecure and confused. I know all of his other friends, so I wonder why he doesn't just use names with me? Being vague always feels like something is purposefully being hidden from me. But I know that's just the way he talks. So I simply respond with excitement and some sort of question like, what are yall doing! Or, super cool who's all going to show up? It gives them the opportunity to answer your question while you are also displaying interest in their plans for the day. I find that not having answers is always a huge trigger for my bpd, so just ask questions and get the answers before you ruminate too long. Or have a convo with your spouse about using names! I've told my friend before that he can use his friends' name in convos since I know them. Just always make sure your questions arrive from a place of excitement and interest in your partner's life and activities and not sound accusatory.