Purple district R's (13 in all) voted for Infrastructure which took away AOC et al's leverage wrt to holding up the bill unless it was coupled together with BBB. Infrastructure was able to pass separately (a loss for R's but much much less than BBB would be for the entire country and themselves).
The R votes allowed the bills to remain decoupled. Had they not been decoupled, large portions of the BBB would have undoubtedly survived along with the Infrastructure bill after compromises occurred.
However, decoupling allowed for the blocking of the BBB plan completely (at least for now and hopefully permanently).
As an additional benefit, each of those 13 house members who voted for the Infrastructure strenghtned their positions in the upcoming 2022 election.