Can my job tell me not to be gay?

My g/f & I both wrk @ Wal~Mart & n the past few months we've bn harred by specific co-workers & have bn pulled n2 the office 2x by a certain manager 4 hugging w/ a kiss on the cheek off the clock (out of uniform) 1st time, & 4 holdin hands on the clock the 2nd; she basically told us we're not allowed 2 hug or kiss inside the store (on or off the clock...n or out of uniform). She wnt on 2 say that she has nothing against us 4 any reason, but that she'd hav2 write us up if she caught us bein affectionate n any way at all. I want 2 believe this but i really don't. There r several (str8) couples wrkn there that make out & dam near have n the open on the clock n uniform & nothing's said & them even wn they're caught. There was another str8 couple that did get caught havn sx n the dairy cooler, & all that happened was a d-day...c'mon...if they were gay...they'd b gone. Should I say something so someone?