Please let me make clear that people are free to use or not use fabric softener as they see fit.
My comment here is basically to just say that we pick our battles -- as a long time husband, I more often than not *notice* what my husband does, but I more often than not choose to keep quiet. I have no idea what's going on your your husband-to-be's head, because most of the time I'm not even sure what's going on in my head, but he may have noticed and decided not to say anything for a variety of reasons.
Or maybe, just like you said, he didn't notice.
But if you are curious, I will say, asking him is the best thing. Possibly even having the conversation *before* you decide not to use it.
Most husbands will not care one way or another until things fall under a certain standard and even then they may or may not say anything.
But I did hear recently from a friend who for whatever reason decided to stop using fabric softener and thought everything was going just fine and the difference was minimal until his husband, who until then did not appear to care about laundry at all asked my friend something along the lines of "your laundry was always perfect, why is it that now it feels so bad?" which led to a conversation about fabric softener and they are using it again.
Good Luck!
-- Paulo.