What's happening? Advice

I'm in my sixties as well as my wife and sex is non existent . The other night though she seamed frisky and before I knew it we were naked and going at it. I can count on one hand how many times I've cum in her mouth in the past. This night she was horny as shit and I'm embarrassed to say my cock went soft ,wtf! She just kept grinding though then she was like possessed and went down and started sucking my dick. It responded well and I would tell her when I was cumming and she'd back off. This was a different story as I told her "ya that's it sweetie ,oh Hun I'm going to cum" she doesn't stop and it shoot a nice load in her mouth. Never ever does she stick around. This time she took her time going to the bathroom as if she swallowed . I asked her what got into her and she won't say. I then said I don't care keep doing what your doing. Ps I've noticed her vibrator has been getting some use. Very unusual . What your thoughts?