I think some wishful thinking is taking place in this thread.
Is she messing around? It is entirely possible.
However, there is no evidence presented anywhere in this thread that can give anyone cause to speculate that she IS messing around.
As others pointed out, the underwear marks are normal - even on a virgin.
It is the entire reason that we wear underwear in the very first place.
The comment you said she gave when she blew you off actually suggests that she is Not messing around.
If she was, her reply would been defensive, or even possibly, would seek to turn the tables on you.
If she was dishonestly messing around, she would likely not say something that suggests that part of her considers the possibility as she had.
That would be the last thing a person with something to hide would say.
The above does not mean she is innocent. But it seems likelier to me given what little has been said...
And that is a good thing since trust and open communication are really quite crucial. And if she is not messing around, that that also implies that you are in a good place with trust.
What you can do is tone back the encouragement. Too much of it makes her doubt it.
Ease off for a while and wait - see if she then brings it up on her own...
If she does, then you know she does have interest in the idea.
It also sounds like you have some trust issues - and that may be feeding your fantasy.
The idea being... IF she is messing around, then you may fear losing her. The mind then begins to cope with that fear by considering "What if she could have her cake and eat it too?"
The trouble with this is that it Does Not Confront the Trust Issues or Jealousy.
Since they are not managed, her messing around With Your Knowledge will still likely have Jealousy and Trust issues.
She will be able to see this... after all, she married you.
When a woman loves someone and sees them in pain; but cannot seem to be able to do anything about the pain the person they care about has - they often slowly begin to cope by letting go of the concern. They stop loving the person in order to protect themselves.
This is a self-fulfilling prophecy, the actions you took to prevent losing the woman end up causing it.
So IF the above applies to you; I would encourage you to examine where you stand on TRUST before anything else.
The comments she made, plus coming home wet, suggests that the possibility is in her mind. Even if she has not acted on it. It sounds like she's not acted on it (I Do Not Know For Sure) and that she has some trust concerns with you, given your comments and her response to them.
So focusing on trust would benefit you both, whether it leads to the Healthy Lifestyle or leads to your relationships health..