If spending time hiking with your loved one is your top priority right now, consider buying a double sleeping bag. It is better to bring one double sleeping bag rather than two single sleeping bags due to its simplicity. Same rules apply: address your needs and preferences first. If you plan to go to hike on a mountain, get the bulky one. Bulkier the bag, more insulation it provides. For backyard camping, consider buying a lighter one. Get one with side zipper since it is better than the center one. Side zipper will prevent the cold wind to blow directly to your body.