Minderwiz
OK, I'll tell this person the answer is "yes" then.
Did you also check for reception?- that is (preferably) the quesited's significator in one of the dignities of the querent, or the querent's significator in one of the dignities of the quesited's significator or even better a mutual reception between the two significators.
Did you also allow for the context - do these two people know each other, and to what extent? If they are already in something of a relationship then the answer is almost certainly 'Yes'
If they are acquainted but there is a reception between the significators, as well as the trine then the answer is probably yes, (or the relationship will intensify even if it doesn't immediately result in marriage)
If they don't know each other, then things are a bit more problematic. Trine plus reception indicates a good chance of a meeting or contact, resulting in attraction and which might develop, though the querent might have to act to get the ball rolling. If there's no reception at all, or the reception is the querent's significator in a dignity of that of the quesited then what you might have is hope that is strengthening but the feelings are not reciprocated by the quesited.
And of course, remember the golden rule - the stars incline, they do not compel. If the querent takes a yes answer to mean it's inevitable and sits back and waits for the quesited to throw themselves into his/her arms, it's virtually certain nothing will happen - having a favourable situation doesn't make things automatic - the situation has to be exploited by one or other party. They might be desperately in love with one another but if neither of them communicates this to the other then things won't happen!