to sink into · to get caught up in · to land in (a predicament)

Now Marina was a romantic; she had not yet fallen into that passive state of mind which accepts that one should find a corner to live, anywhere, and then arrange one's whole life around it.

In adolescence, I hated life and was continually on the verge of suicide, from which, however, I was restrained by the desire to know more mathematics.

You're getting into deep water.

He deliberately exposed her to danger.

It was in 1832 that Evariste Galois fell in love with Stephanie-Felicie Poterin du Motel.