You could nearly call it a ‘celebration’ session because as cheesy as it sounds, that what it’s all about! - celebrating your love. They are lots of fun and a great chance for you guys to just hang out and have a great time.
I personally did some photos for my parents on their 25 year anniversary and I know that I will treasure these images myself for many years to come and many years after they are gone.
For others you may have just been together for a long time or you may be celebrating an engagement! This is a milestone in your life worth capturing!