Question: May a man have yichud in a back room (e.g., a den) of a house when the front door to the house is open?

 Short Answer: Yichud is permitted in a back room if the front door to the house is open (or according to some poskim, merely unlocked) and the back room is open directly to the front room. There are some poskim, though, who might permit it even if the door to the back room is closed (but unlocked).

Question: Is there a prohibition of yichud when two frum men are secluded with one frum woman?

 Short Answer: Assuming that both men are upright men, there is no problem for two Ashkenazi men to have yichud with a woman in a city during the day. The exact definition of “upright,” though, is subject to dispute.

Question: Is a man permitted to have yichud with a woman in Kew Gardens Hills when his wife is in Woodmere?

 Short Answer: Some poskim are lenient if his wife may return home at any point. However, many poskim would prohibit, either because there is no such leniency for a husband, or because Woodmere is a different city from Kew Gardens Hills.

Question: Is it a prohibition of yichud for a boy and girl to go hiking in a state park on a shidduch date?

 Short Answer: Assuming that the park is frequented by other visitors who will be able to see the shidduch daters every few minutes, it is permitted. There is further discussion, however, in the poskim whether the shidduch daters violate yichud when going in a car together on secluded roads.

Question: May a person act leniently when faced with a situation that is possibly, but not certainly, yichud? 

Short Answer: There are many poskim, including Rav Moshe Feinstein zt”l, who appear to allow one to act leniently when faced with a situation that is possibly, but not certainly yichud d’Rabbanan (Rabbinic).