This market is part of a post: Manifold for CBT
From quick googling, seems like a chance of a random US male getting married for the first time before he is 34, given that they are not married by 25, should be about 40%. Since those markets are not heavily betted yet by some friends of yours who have more insider info, I suppose I can go with that rough estimate.
In general, it really depends on how much you value finding a partner, getting married, having kids, and all that jazz, because finding a good partner requires a LOT of time and effort. If you value that enough, I would recommend committing to it, establishing a measurable proxy goal (to go on 50 dates next year or smth), tracking it regularly, and doing a real effort with all you've got since this is something that is actually important to you.