It's seems to be common enough as it's happening to a friend of mine who's getting a divorce when they should be celebrating 5 years of marriage

most of us men just find ourselves "married". The lady comes to the house and settles and your story is over. You mother likes her, your sisters like her, your brothers say she is great, your aunt says she is very wonderful and you are finished. Junior comes and pressure is mounted by your folks. "Wewe mbona unakaa na mtoto wa wenyewe bila kupeleka mali?". So the wedding thing is finally put into your head. You do the harusi thing later when the babies have started going to pre-unit. And that is the best marriage. Majority of the stay.

Lakini hiyo ya @njuno friend is a non starter. By the way, @njuno, tell your friend to learn the art of domesticating first.

I think it is like 2 Cents said ....she has met someone new and wants to keep the poor guy as back-up while she sees how this new thing develops. The warning lights should have gone off when she said she wants some space; Usually its the woman who applies lots of pressure to walk down the altar, even when she knows the dude is fairly in and in unlikely to run.
If it was me,... I would walk.

Mwanamke siyo loan. Move on

Gosh...its amazing..the things that go through guys minds to papasa papasa their egos...ati "there are women who really wanted me to marry them..."