bone of contention

(noun) a problem that keeps on happening

Example Sentences:

A: Are you having a good time with your roommate?
B: Yeah, but one bone of contention between us is that he is so messy.

A bone of contention between the husband and wife is that the husband always spends too much money.

From the Blogs:

Bone of contention in delivering Quality

Media:

Similar idioms:

1. have a bone to pick with someone
2. work one’s fingers to the bone
3. give and take
4. pick up the check
5. pick up the tab
6. check in with
7. golden handshake
8. open up a can of worms