Relationships can be tough, especially on sitcoms. So it’s encouraging to find Fox’s “The Mindy Project” and “New Girl” each beginning their season in relatively fine form, with one adjusting to the complications of a new in-show romantic entanglement, and the other seeking to rebound from having indulged in its own. Although neither show has been an unqualified hit, they’ve done well enough to hang on, and scheduled together feel like a compatible little island of 30-ish neuroses, on a network with enough problems elsewhere that – barring a major swoon – it would probably be wise to just leave them alone.

“New Girl” stumbled a bit by succumbing to the risk of having the quirky Jess (Zooey Deschanel) hook up with one of her roommates, Nick (Jake Johnson), even if all the signs had been pointing in that direction. As shows such as “Cheers” and “Friends” learned, bringing characters together in this fashion invariably changes the dynamic, while closing some doors, narratively speaking.

Yet any awkwardness associated with the breakup is relatively modest in the season premiere, which finds the entire gang attending a wedding, making a pact in which all of them will try to go home with someone. Jess sets her eye on the best man (“Veep’s” Reid Scott), who has unfortunately already drawn the attention of another woman (guest Jessica Biel, nearly stealing the show), who proves formidable competition. Meanwhile, the walking id Schmidt (Max Greenfield) prods Nick toward a group sexual encounter that raises questions about just how close buddies can get before things start getting weird.

As for “Mindy,” Mindy Kaling’s eponymous character is fully embroiled in a workplace romance with fellow doctor Danny (Chris Messina), which is complicated by her inability to edit herself. In the premiere, that includes bragging to all of their co-workers about Danny’s prowess in bed (OK, at one particular activity), which embarrasses him and offers a window into their mismatched personalities.

Frankly, the series still remains a trifle weak in terms of the support staff, and the opener’s secondary plot feels even more disposable than usual, a description that also applies to a mildly amusing cameo by “It’s Always Sunny in Philadelphia’s” Rob McElhenney. Still, the interplay between Kaling and Messina is actually quite good – much better, in fact, than their squabbling when they were at each other’s throats earlier in the run.

With the two having become a couple, the trick will be not turning the show into a modern-day “That Girl,” where the exasperated Danny is constantly rolling his eyes over the misadventures into which Mindy has drawn him.

Fox is already gambling by scheduling live-action comedies (including a relocated “Brooklyn Nine-Nine”) alongside animated fare on Sunday nights this fall, so it can ill afford to have these Tuesday holdovers experience a significant decline.

The good news is if you’ve enjoyed the shows in the past – and perhaps felt “New Girl” lost a bit of its fastball – the kickoff episodes suggest there might be more to like in the year ahead. The bad news is that both enter the fall campaign without much margin for error – either creatively speaking, or ratings-wise.

TV Review: Fox’s ‘New Girl,’ ‘The Mindy Project’

(Series; Fox, Tue. Sept. 16, 9 and 9:30 p.m.)