Jerry and Elaine: OCEAN Compatibility Profile

Jerry and Elaine make the case that some people are better as exes than partners. They dated before the series, split, became inseparable, and keep half-circling back to romance without ever committing to it. The 30-facet framework explains the whole loop with a single point: these two are unusually alike, and that likeness is what makes them great friends and doomed lovers.
Basically the same person
The profiles track each other closely. Openness sits at 54 and 58, both land on the calm side of Neuroticism, and the real tell is Agreeableness, nearly matched and very low at 19 for Jerry and 24 for Elaine. Cynical, blunt, quick to judge, allergic to sentiment, they run on the exact dry wavelength the whole show is built around. For a friendship that's close to ideal. They find the same things funny and neither one needs the other to be warm, which works out because neither one is.
Why the match fails as romance
A romance needs a thing a friendship can skip: some way to settle a fight, which usually means one partner willing to give ground. Neither of them can. Assertiveness runs high at 75 and 85, Cooperation is nearly matched and very low at 24 and 23, so a dispute leaves you with two strong wills and nobody built to fold. Friends never hit that wall, because a friend can just let it drop and go get coffee. Put the same two immovable people in a relationship and they'd stall on every decision that mattered, with no warmth to soften the standoff, since the shared low Agreeableness strips out the tenderness that lets other couples ride out a deadlock.
The friendship is the right call
Everything that makes them work as friends is what would wreck them as a couple, and they seem to sense it. Low mutual Agreeableness starves a marriage but costs nothing between two people who never wanted warmth from each other in the first place. Two high Assertiveness scores gridlock a partnership yet stay harmless when the only argument is where to eat. So each time they drift toward romance and then pull back, they're reading the situation correctly: the same traits point one way for a friendship and the opposite way for a marriage.
Jerry and Elaine show that being alike isn't the same thing as being compatible. Alike is plenty for a friendship, which mostly asks that you enjoy each other. A romance also wants conflict you can resolve and warmth you can offer, and on those two axes a pair of matched, low-Agreeableness, low-Cooperation people are badly equipped no matter how well they click. These scores came from the same 30-facet OCEAN personality test that you and someone in your life can each take in about 15 minutes, with domain results free, and a compatibility report will tell you whether a strong connection is built for friendship, for romance, or, like this one, firmly for the first.