You may have to carry more stuff if you go alone, but solitude is a special reward and well worth trying at least once. The Rae lakes loop follows very established trails and would make an excellent choice for a beginner solo trip. Don't let your partner's absence stop you.
Very well said. Don’t let this be the reason why you didn’t go! The Rae Lakes Loop is a very populated trail. If you’re a novice backpack then I think this is a GREAT hike to solo on! Now, the question is just the added weight to your bag. Plan accordingly, and have fun!