C+ dater

class c_plus_dater:
    def __init__(self, nrof_bots, rng): # rng is a seeded PRNG you can use, no other forms of randomness allowed
        # nrof_bots is the total number of bots playing
        self.round = 0
        self.betterbots = 0
        self.bestbot = None

    def round_finished(self, nrof_remaining_bots): # the number of bots still in the game
        self.round += 1

    def date(self, other) -> bool: # Return True if you want to marry this bot, False otherwise
        if self.bestbot is None:
            self.bestbot = other
        else:
            if other > self.bestbot:
                self.betterbots += 1
                self.bestbot = other
        return self.betterbots >= 3

Edited to avoid comparing a bot to a constant, instead only to each other. This bot takes any bot that is better than at least 3 other bots.

Old version: Bot takes anything above 70% in the first round, and lowers its standard each round after that.

[I'm counting on compatibility being between 0 and 1]