Mac and the waitress do hand stuff.

Addressed the Charlie and Dee thing below; I just don’t consider a one-off, single-episode B-plot like that 10 seasons into the show (with a later throwaway joke in one episode three seasons later) a “romantic entanglement” for what’s an ongoing 17-season comedy show.

Mac’s crush on Dennis is the closest we come, but that’s still very distant from “romantic entanglement” to me; that implies an entanglement, where in reality Mac’s one-sided crush is infrequently referenced and pretty much always for laughs, and Dennis clearly demonstrates at every turn that literally nothing will ever come of it. The audience is always deliberately shown that this will never turn into anything; there’s no “will they, won’t they” going on because the answer is always and in perpetuity “won’t they”.

TL;DR: There’s no actual arc or plotline.

Yeah, it does happen, although I still went ahead with the comment because I don’t consider that a “romantic entanglement”.

• The show has 178 20-ish-minute episodes over 17 seasons.
• Of those, there’s one B-plot in one episode (“The Gang Misses the Boat”) ten seasons in and a later one-off reference to it in “Time’s Up for the Gang” (S13).
• The show has mostly minor elements of serialization, and there’s no ongoing romance between the core gang at any point; if you accidentally missed those two episodes (or one and walked away to get a drink without pausing for like a minute on the other), you’d literally never know.
• Arguably the closest we get is Mac’s obvious crush on Dennis, but this only comes up infrequently, is rarely played for any kind of actual drama, and is almost exclusively a punchline, and Dennis never reciprocates in the slightest.

“Entanglement” to me implies that the two or more characters have ongoing, mutual romantic feelings for each other that are explored or at least consistently shown over multiple episodes.