I don't see why that is unreasonable. There is a finite amount of time, building a relationship takes "one on one" time, and if you had a full life pre-relationship with work, school, sleep, reading, travel, yoga, dance, friends - well something has to give, right?
I know when my friends (men and women) are involved or getting involved with a new partner, and understand that we can't see each other that often, it doesn't take much to just call them once in a while and say Hi. I am also lucky in having friends who give me the same understanding, inviting me over when I am single, inviting my "date" to get to know her, involving my LTR partner in stuff, and yes, being there for me when something serious ends.
Perhaps your friends and the men with whom you seek relationships need to grow up, and we should all be careful to not learn the wrong lessons from our limited experience or "past boyfriends".