Pity-smash
An affectionate low level hook-up often made in commiseration, with no serious emotional involvement on the part of the smasher, but sometimes inadvertently on the part of the smashee. Essentially a modern update of the 80s/90s 'Sympathy Fuck'.
Sue pity-smashed Tom after his break up with Helen, and now he thinks it's serious and won't leave her alone..