行っていらっしゃい: alternative form of いってらっしゃい (itterasshai)

see you later (said by a person staying, a stock phrase required by the Japanese etiquette, lit.: (after) going, come back)

not in the mood to do things; having a heavy mood

relying heavily on

to rely heavily on

(humble) alternative form of いってきます (itte kimasu)

back and forth

(colloquial) Synonym of 行って来ます (itte kimasu, “see you later”)

to go and come back

not straightforward; not dealt with by ordinary means