How did I get this? Fuzzy logic, mostly. Tom strikes me as extroverted, since he makes the first moves on both Jane and Daria, and he does get around a bit (i.e., he's not "antisocial" like Daria). He's unconventional in how he conducts his love relationships (not meaning the triangle thing, but more in how he likes to spend time with a girlfriend). He refers to normal dating habits as "corny crap" in "Sappy Anniversary," an episode that reveals a lot about his views on romance. This isn't necessarily bad, as he can intuitively pick out the right thing to do at times, like that special dinner for Jane with the music, etc. "All I did was meet a girl I thought was cool and I went out with her for a while," he tells Daria in "Dye! Dye! My Darling." "We started to get bored with each other. It happens all the time. It's nobody's fault." In other words, he, like Jane, is prone to change his mind, and he accepts that conflict is a normal part of life. Combine that with his intellectualism and his missing of emotional cues in both Jane and Daria, and he comes out as an ENTP.
What is an ENTP like? The following links will help.
More interesting still, some websites about INTJs (Daria's type) say that the ENTP is a natural mate. No guarantees there, of course. Jane and Quinn both comment (in DDMD and IIFY?) that Daria and Tom would make a good pair. That it didn't work out for Tom doesn't mean it won't work out for another ENTP. INTJs are also attracted to ENFPs and to ESFPs, say the websites.
Wait a minute. Didn't we already talk about ESFPs? Why, yes, we did.
Oops. More on this personality stuff later. Amazing what you can still drag out of a show like this, isn't it?