Did she lose interest in me over the past few days?

It's quite possible, but she might just have needed a break away from you for a little bit, simply to get some space. Some girls need that separation period after getting serious and being with someone a lot. So this trip to the country house i'd say should be fine, and a strong oppurtunity for the two of you to bond more. Go for it! And plus, what do u have to lose?!