Denshi Jisho — Online Japanese dictionary

Couldn't find anything for 填まり込む~, so trying 填る instead.

填る はまる 1: (Usually written using kana alone) to fit; to get into; to go into;
2: (Usually written using kana alone) to be fit for (a job, etc.); to be suited for; to satisfy (conditions);
3: (Usually written using kana alone) to fall into; to plunge into; to get stuck; to get caught;
4: (Usually written using kana alone) to be deceived; to be taken in; to fall into a trap;
5: (Usually written using kana alone) to be addicted to; to be deep into; to be crazy about; to be stuck on
Irregular okurigana usage, Godan verb with ru ending, Intransitive verb 

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