Most teenage boys worst fear is to die being a virgin! LOL
I'm not certain if having sex with a grown woman who is a (stranger) would damage their psyche. Most guys do not place a high value on their virginity and therefore do not have the mindset of "I'm going to save myself for the love of my life." If anything they're more likely to brag about all the sex they haven't really had!
Having said that if a teenage boy has sex with an older woman who is a constant in his life there is a good chance that he may form an emotional attachment or believe they have a "relationship". Naturally this is likely to lead to experiencing heartache once he sees her dating men in her age range.
Last but not least once a guy has sexual experience he is likely to expect to have sex with most of the girls he dates. If the older woman "taught" him any skills he will apply them in his seduction process.