Well, it might be because of the child. Child birth really loosens the walls of the vagina. I think she could go to the doctor and get it stitched up some way and she could do kegels every day. About 80 of them. Give her up to 3 months, she should be significantly tighter. It does not mean she is having sex with someone. I think weight gain has something to do with it, I am not sure but the looseness of her vagina does not say she is cheating.

And lets not forget, more frequent sex stimulates and exercises muscels of the vagina. In my opinion giving you more control and strength.

The pelvic bone (s) and surrounding area is expanded duing the babies growth/birth and if the bone structure is spread apart, how would it contract to it's original position? It doesn't. All the females i've encountered that had a baby, had this happen to. Just as females that had no children yet, have been still "tight". (as per person) Teenagers, 20s',30s', 40 year olds, squeeze that pinky finger hard, if no birthing had orrured yet....first child, though at any age, and whammo.....'el stretcho....thank god we guyz have it made! these females go thru heck during their life...

a vagina is different than a labia. Labia is the flesh on the outside.

The OP is talking about her vagina. The vagina is the hole, basically, not the outside decorative flesh.