Our two characters (played by Jason Sudeikis and Alison Brie) are in their early/mid thirties who met each other briefly at college. They both are stuck on some issues from their pasts that have lingered on till the present day. Through first and second-hand experiences, I have seen people go to certain lengths trying to resolve complex emotions shaped during formative years of their lives... So I found these characters realistic and relatable.
Sleeping with Other People's core is the emotional psyche of its characters and this is what differentiates Sleeping with Other People from When Harry Met Sally. Yes, the male characters in both movies have similar views on the relationship between men and women - namely, that they cannot be just friends. Both characters ignore their rule and become genuine and supportive friends for the female protagonists of their respective movies, but that's where the similarities end. Sleeping with Other People shows how these characters help each other overcome their issues from the past and break those shackles. In a sense, they help each other grow... This development is what made Sleeping with Other People a distinct movie for me.
The ending (particularly the last five minutes) was a little cheesy, but that aside, this was a 8.5/10 for me - in the rom-com-dram category.