I would recommend the following for the best place and best restaurant for the first date in Kathmandu. The first date is very important and very sensitive, it is the step towards whether to continue or end it.
Jawalakhel Zoo or Boudha Stupa. The zoo cause it has lots of space to walk around and if there are certain situation where the conversation tends to pause, you have lots of topic to talk about..the animals. My favorite part is renting the boat and take the partner for a boat trip. It will be a memorable experience. Boudha Stupa cause very few people care about who you are and talk about you. Also, they have good coffee shops with a great view and good deep conversation to have.
There are many choices with great food in the capital. I haven’t had the privilege of visiting all. They keep on opening up and closing down. Now to narrow down to two.If it is the breakfast date or brunch, i recommend Bodhi and Books. They are just opposite Kantipur School at Maharajgung Chakrapath. They are a bit different and you can just enjoy the conversation with nice cup of coffee. I was going to say at Himalayan Java but what differs this cafe is the people visiting the cafe are different, with other mindset. Just visit to experience it. For the late afternoon date or dinner i recommend Zen Cafe and bistro. They are located 500 meters above the Australian Embassy,in the opposite side. They have a great ambiance and have many different themed restaurants inside. The service is great and the food is tasty. Try their Tom Yam Soup,share it with your partner. It is a ice breaker.