Desire is not constant, and that is normal
Sexual desire is not a fixed quantity: it shifts between people, between couples and across a life — pregnancy, early parenthood, mental load, work exhaustion, hormonal change. A temporary dip is not in itself a sign of relationship trouble. It becomes something to work on when it settles in and one or both partners are unhappy.
Sexology distinguishes spontaneous desire, which appears unprompted, from responsive desire, which is triggered by a stimulus — touch, a relaxed setting, closeness. Many women, and a fair number of men, run mostly on the second model: desire arrives after touch has begun, not before. Waiting to "feel like it" before getting close can therefore maintain the very dip you are worried about.
What sustains desire over time
Unpressured time together, talking about what each of you actually wants, novelty (a different place, time or pace) and the quality of the relationship outside the bedroom all matter at least as much as technique.
How female orgasm works
Orgasm in women usually results from direct or indirect stimulation of the clitoris, whose nerve network extends well beyond the visible part. Some women reach orgasm through penetration alone, but the majority need additional clitoral stimulation — which is entirely normal and not a dysfunction. Arousal also tends to build more slowly on average than in men, which is the practical argument for unhurried foreplay.
Pleasure depends on context as much as on the body: emotional safety, absence of judgement, and being able to say what you like. Simple words during sex ("slower", "keep doing that", "not like that") change more than any new technique.
When to seek help
A lasting absence of desire or pleasure that worries or distresses you can be worked on with a psychosexual therapist, alone or as a couple. In most countries an accredited professional body publishes a register of psychosexual therapists, and your doctor can also refer you; some public health systems offer the service directly. It is neither shameful nor reserved for couples in crisis — it is healthcare like any other.