The Waterfall by Margaret Drabble.
Jane Gray - no, not that one - is having a mixed time of it. A published poet - hooray! - but not writing much these days - boo! - and about to give birth to her second child with husband Malcolm - hooray! - who has just moved out of the family home after an irretrievable breakdown of their marriage - boo!
Luckily she has a bit of help managing this emotional rollercoaster from her cousin Lucy and her husband James, not to mention some more practical assistance with giving birth at home (to a daughter, Bianca, to go with son Laurie who is about three) and subsequent basics like getting to the toilet and acquiring shopping.
We get a bit of back-story now: Malcolm is a guitarist and singer, quite highly-regarded in the particular musical circles he moves in (vaguely folky, maybe even a bit classical, as far as we can gather). The exact circumstances of his and Jane's split aren't made completely clear, but there seems to be an implication that Jane suspects he might secretly be gay - nonetheless it seems that post-split he has managed to shack up with another woman, so who knows. James, on the other hand, is a slightly shady car-dealer and occasional amateur racing driver.
Anyway, any doubts about the irrevocability of the split are soon, as it were, put to bed, as James' extreme attentiveness to Jane's welfare extends to his volunteering for helping-out duties without Lucy in tow and, during one of these, ending up in Jane's bed for a bit of light and cautious post-partum firkytoodling. The relationship continues as James' "business commitments" allow him a plausible smokescreen to be away from Lucy for days at a time, time he spends popping over and being jovial Uncle James for the kids for a while before taking Jane upstairs for a good seeing-to.
Eventually a "business trip" presents itself that offers an opportunity for James and Jane to get properly away, in this case to Norway where he is personally delivering an Aston Martin to a customer - inevitably in some shady way involving dodging tax, duty and/or insurance. The trip involves catching a ferry from Newcastle and so James and Jane and the kids head off there in the Aston Martin. All goes well until the car hits a brick dropped from a lorry ahead, flips over the central reservation, gets hit by an oncoming car and ends up ploughing into a tree on the opposite verge. By some miracle Jane and the kids are unhurt, but the driver of the oncoming car is dead and James is severely injured. All a bit awkward for Jane - James was scheduled to be away for two weeks, so as long as he recovers within that time they can get away without being rumbled. But James' injuries are more serious than that, and, in any case, what if he dies? Don't Lucy and his parents have a right to know? Jane bimbles around uselessly for several days until the decision is taken out of her hands by Lucy phoning her at her hotel - Malcolm has rumbled them and told her and she has made the necessary enquiries and found out what's happened.
Thankfully it turns out that James will make pretty much a full recovery - after Lucy arrives and takes charge of his convalescence it becomes clear to Jane that their affair will be over, though once he's recovered they do manage to meet up for a bit of valedictory fucking. Jane finds herself OK with this and moreover finds that the experience has rekindled some of her poetic inspiration.
So what to make of this? I recall in my short but rambling review of Drabble's A Natural Curiosity back in the very very early late-2006 days of this blog I bemoaned not quite grasping what the book was meant to be about or what its purpose was. I think I have similar feelings here, although I guess I do see some of the purpose: The Waterfall was written much earlier in Drabble's career (1969) and embodies some proto-feminist themes like female independence, female control over sexuality and fertility, not having to settle for a man just because he is the major breadwinner and father of your children, getting sexually involved with men just because you want to rather than for any ulterior motive involving marriage or support. That said, and despite the back cover blurb describing the novel as "a bitter-sweet song of sexual love", there's never much insight into what attracted Jane to James in the first place. We don't get any clear sense of unstoppable lust from either participant, especially not Jane who is a strangely inert and passive central character. James' motivations are similarly opaque, and even allowing for his business trips it's unclear how he's able to conceal the affair from Lucy.
Those considerations aside this is perceptive in its observations about 1960s sexual politics and the messiness of love and childbirth, without any of the central characters being engaging enough to really make you care very much about what happens to them. I'm not sure I really buy its being described here as "experimental", unless that refers to the occasional shifts between first-person and third-person narrative voices; this seems like a very low bar to clear for "experimental" status, though. I think Margaret Drabble probably suffers a bit from her surname being ripe for cheap puns on the word "drab" as well as other related puns. Of the three novels I've read from her lengthy career The Radiant Way is probably the best.