The window opens in a dasha (the timing)
Marriage usually arrives during the major or sub-period of your 7th-house lord, of Venus (Shukra, the karaka of love), or of Jupiter (Guru, the karaka of marriage). The practical way to answer "when" is to find which Vimshottari dasha you are running now and which one is next, then see when a marriage-activating period opens. That is the real timeline, not a generic age.
The promise lives in the D9 (Navamsa)
The Navamsa — the divisional chart of marriage — is where the promise of a strong, lasting union is actually tested. A 7th house that looks promising in the main chart but weak in the D9 is "more visible than real"; the reverse means a quiet marriage that holds. Reading the D9 alongside the dasha is what separates a real answer from a horoscope.
Why it gets delayed (and what that means)
Delay is usually Saturn, not denial. Saturn on the 7th house or its lord postpones marriage until the foundation — stability, self-knowledge, the right person — is genuinely there. Mangal Dosha (Mars) is the other common factor, and it is widely over-feared and frequently cancelled. A delay in the chart is almost always protective, not a closed door.