せいで

Because of, owing to. It marks the cause of an undesirable result and often implies blame on that cause.

Used in everyday speech and writing to explain why something bad happened, often expressing dissatisfaction or blaming a person, thing, or event. The main clause describes an actual negative result. For favorable outcomes, おかげで is used instead.

• おかげでN3「おかげで」 is mainly used for good results and carries a nuance of gratitude; good results are normally not expressed with 「せいで」 (using it that way comes across as joking). It can also be used ironically for bad results, but with a sarcastic tone, unlike the direct blame of 「せいで」.
• せいかN2「せいか」 does not assert the cause—it only suggests 'maybe because', with a weak sense of blame; the following clause often takes expressions like 「気がする」, and it can occasionally be used for neutral results. Its attachment pattern is basically the same as 「せいで」, so when the cause is certain, 「せいか」 is not an appropriate substitute.
• ばかりにN2「ばかりに」 also indicates a cause leading to a bad result, but it usually carries regret or disappointment and emphasizes that the cause was trivial; it leans toward written style, and nouns must take 「である／だった」. There is also the pattern 「〜たいばかりに」, meaning 'desperate to...'.
• ためにN3「ために」 can express purpose as well as cause. When expressing a cause, its tone is objective and rather formal, without any sense of blame. Both can be used for bad results, but only 「せいで」 carries the dissatisfied nuance of 'it's all because...'.
• のでN5「ので」 neutrally states a cause and works with both good and bad results; the following clause can also contain requests or suggestions. 「せいで」 is normally used for bad results and carries a tone of blame. With nouns, use 「なので」 for 「ので」 and 「のせいで」 for 「せいで」.

おかげで credits a cause for a good result. せいか suggests an uncertain cause ("perhaps because"). ばかりに stresses regret that one single factor led to a bad outcome. ために is a more formal, neutral cause marker. ので states a reason objectively, without blame.