Another issue that I get questions about from audiences or which comes up when I do counseling with singles is how many people to go out with at one time.
It seems, in my experience, the issue of how many people to date simultaneously often tends to come up in proportion with the increasing age of the single in question, meaning to say, the older the individual is the more he or she intensely wants to see more than one person at a time.
An exception might be when an "out of towner" comes to a big city and is pressured to see as many "candidates" in that city as possible in a relatively short period of time (which can entail halacha [Torah law] problems). If you are going to a distant city for a barrage of dates, get guidance from a Torah law authority.
Because emotions and personal biases get involved, and because there are considerable Torah principles involved, seeing more than one person at a time (for any reason) is a serious question as a matter of practical Jewish law. This is particularly serious because this involves interpersonal obligations to other Jews (if you recall, we spoke about the severity with which Heaven judges person-to-person behavior).
I have spoken a number of times on this issue with Rav Chaim Krauss, Rav of Congregation Ohel Chayim and posaik (decider of Torah law) in Brooklyn. Dating more than one person entails halachic (Torah law) questions, for example:
1. kavod habrios (obligatory and practical human dignity)
2. g'naivas da'as (deception, misleading)
3. bitul z'man (wasting your own or another's time)
4. bitul momon (wasting money - your own or someone else's).
Rav Krauss says that as each situation arises, ask a shaalo (take each individual question to an orthodox rabbinical authority for specific case-by-case instruction).
Also, often, in my experience, I see that the more one is driven to see more than one person at a time, the more the person tends not to be ready or equipped for a stable and committed marriage relationship.
Alay Shur defined the attainment of readiness for marriage when becoming able to emphasize giving and responsibility for the good of another and de-emphasize taking and irresponsibility in regard to others. Marriage is axiomatically readiness for the commitment, giving, responsibility, faithfulness, intimacy, bondedness, unselfishness, midos, self-control, and maturity, such as the marriage relationship demands.
Marriage requires full attention and devotion to one partner. If you can't do it before marriage, you don't automatically become able to it just because you've pranced through a chupa. The chupa transforms your marital status - not who and what you are as a human being.
Success after marriage begins before marriage. The person who you are after marriage begins before marriage. Not being prepared to successfully relate to one person before marriage is one of the main reasons for today's staggering divorce rate and "shalom bayis epidemic."
There is, therefore, even more than the inescapable obligation to give derech eretz to the first person you are dating and the prohibition of practicing deception with the second person you are dating (who believes that you are giving full consideration and attention during the date). If a guy spends money on a girl and half of her mind is on someone else, there could be an element of robbery if he is dating her and he thinks that her mind is giving full and fair consideration to him. Comparing or otherwise giving less than full consideration is near-inescapable. Appreciate the practical obstacles to developing a real relationship with either person.
Dating more than one person is referred to as "efficient," as if some kind of virtue. Human relations require standards and attentiveness. Efficiency is irrelevant, and when it takes your concentration away from someone, it is destructive.
Everyone who wants to date more than one person at a time says that they can "handle it." Almost without exception, in my nearly twenty years of experience, these are people who have difficulty forming stable or lasting relationships. I suggest that they "can handle" two relationships because they are not prepared for one commitment relationship. By what standard are they "handling it?" Even if a person could "handle" two mature, judicious, fair, complete relationships, it still can be like a person saying, "I can HANDLE traif, working on shabos or cheating in business," which are also a lack of self-control, discipline and the inability to prevail over spiritual tension.
Remember that one of the very few things that we can take when we pass onto eternity is the tests from Heaven that one has passed in this life. Not seeing more than one person at a time includes NOT meeting a second person coming in briefly from out of town, if you are already seeing a first person already. This is a SERIOUS shaalo (Torah question for a rabbinic authority in Jewish law).
One woman, sincerely concerned about Torah law, said that she was seeing a fellow who was nice but bland. She inclined to think she would not marry him, but her decision about escalating or ending the relationship was not concluded. He had some good qualities that were worth her consideration. She was offered a "set-up" with a fellow who seemed more suitable than the first. The second fellow called her and they both very much liked how the call went. She phoned me to ask me if she could accept the second fellow's invitation to go out. I told her, using guidelines worked out with Rav Krauss, that she has to conclude one way or the other with the first fellow. I told her to tell the matchmaker who gave her the second "set up" about the first relationship. Say that she will call the matchmaker back promptly if she breaks up with the first man. THEN the matchmaker could tell the second boy to call for a date, stressing that the second boy was very nice (so that he wouldn't feel hurt or rejected) and that her present refusal was exclusively because of her still being in the first relationship.