I assume you are talking about eating the creampie you made in your wife? If so.....
Tip 1: My wife has always loved oral, but I found out that she REALLY loves oral after I cum in her! Like.... A LOT! Makes her orgasm better than anything and everything. It turns her on, so I do it! Only one way to find out if yours is into it as mine is....just go for it.
Tip 2: All her enthusiasm she has when I eat her after cumming in her pussy, on cumming on her pussy, and all that hip bucking, ass gyrating, body trembling she does when she cums, is an absolute turn on, and gets me hard again, and wanting to go at it or something else again! Her too! So....if you are one & done types like we were, you may not be anymore! (Betcha can't eat just one!)
There's the best reasons I know of!