This is something very common especially in gym house where there are so many opposite sex working out on daily basis. If you are very observant with how most gym members dresses, it would be very obvious to see that most of the ladies look so sexy especially when they swear on their workouts outfit. So, it's only natural and normal for most guys at the gym to hit on the female members using the gym to carry out their exercises.
As a man, I can honestly tell you that I have hit on a few female gym members which I am currently friends with some as there is absolutely nothing wrong with it. One thing I found out along the way is that most of them are having the same feelings as we men do, so it's a mutually beneficial feeling where no one gets hurt in the process.