To be fair to the Dev during the scene where Bella sucks the masseuse's cock for the first time, and deep throats him. The MC appears surprised that she's able to do this, so skilfully with such a big cock. Which appears to back up this scenario, where she was previously sucking Henry's cock during college.
I didn't expect that she could take a dick so deep.
You could see how the huge dick was stretching her throat, it was amazingly beautiful, a kind of art.
At the same time she forcefully pulled Tom towards her, only occasionally stopping to take a breath of air.
God, where did she learn this?
A possible alternative interpretation of that earlier scene, is that Bella is feigning her surprise, because she doesn't want the MC to think anything happened between her and Henry, in the past. If she wasn't surprised by his size, the MC would almost certainly become suspicious, wondering how she could possibly know that his friend had such a big cock?
Now do I believe that was the original plan? Possibly not? But there is circumstantial evidence to back it up, which was added to the plot, much earlier than you suggest.