Throwing it out there, could it be possible she has gone on other dates to try make your man jealous especially after being burned the first weekend she abruptly came back and he may not be showing further interest in pursuing a romance?
She's trained at his gym but maybe it was an arrangement to get him publicity while at the same time she is very thirsty for him, has told all her friends similar and it's backfired but she is pretending there is something going on.