Someone commented on her post it was quick and she jumped in to explain she'd emotionally left the relationship much earlier than they announced etc. I don't have a problem with the speed of dating post divorce, but moreso this is so so so quick to jump into an engagement and gives off a lot of red flags. You can't be in love with someone that quickly. Love takes time and trust. You can lust after someone that quickly, you can love their personality, love spending time with them... But real love is built over a longer period of time. Also alarming how quickly they have introduced each other to each others kids. All classic signs of love bombing as it falsely speeds up the relationship and intensifies it.
It might be fine, and I also might be on higher alert than most as my last relationship started out very similar to hers - the seemingly instant connection, saying I love you very early on, extravagant gifts, introduced me to his kids within weeks of knowing each other, moving in together very quickly - and it turned out to be an emotionally abusive relationship. We were together 5 years before I sought out therapy (thinking I was the issue) and it took another 2.5 years for me to realise the extent of the abuse before I finally got out. Hopefully it's not that, I wouldn't wish that on anyone. Looking back now the love bombing was obvious but I couldn't see it at the time.