I'm working as a part of a team, I'm a backend developer. I work with two front-end developers.
Last three sprints we missed delivery on things that were related to the front-end.
My work is usually (not always) without problem and finished on time by end of the sprint. So much so I have time for refactoring, fine-tuning testing data sets, and some other nice-to-have maintenance tasks.
I really put myself into my work and if I can I always go the extra mile. However I don't feel the same from my front end developers, they don't care too much, and are quick to blame when there is an issue and overall I'm not satisfied with their work (I have worked on frontend projects before and I know what good UX looks like - you have to care and work from your own initiative and have to fine-tune every little detail).
When I count lines of code it supports my hunch they just don't do much. Last sprint reflecting on this I offered my help to work on the front-end so as to not jeopardize our roadmap and keep the project on schedule, but my offer was declined and created tension within the team.
Normally I would mind my own business but this starts to affect my motivation and is really anticlimactic to see we are missing one delivery after another. I would like to bring this up on our next retrospective but I'm afraid I would be too harsh and unfair.
Can someone please share what are DOs and DON'Ts when talking about this sensitive topic?