Potential form verbs followed by adjectives to end a sentence have to be in te form?


Do potential verbs followed by adjectives ending a sentence have to be in te
form?

For example

> 見られて嬉しい

instead of

> 見られる嬉しい.




Yes, [potential form in _te_ -form] + [ _i_ -adjective] is a common pattern.
For example

> 逢えて嬉しい（です）  
>  I'm glad we met / I'm glad we were able to meet

> 消防車に乗れて楽しかった（です）  
>  Being able to get on a fire truck was fun

From a grammatical point of view, you cannot combine a verb in its basic form
(e.g. 見られる) with an _i_ -adjective / adjectival verb (e.g. 嬉しい). You could
nominalize the verb (e.g. 見られるのは嬉しい), but it would read like a general
statement, like "I enjoy being watched" (if 見られる is passive) or "I enjoy being
able to see [new things, say]" (if 見られる is the potential form), but the latter
is maybe not as natural as one would usually use the standard form rather than
the potential form.

Using the _te_ -form shows that the verbs happened in sequence, giving a
notion of causality, like

> 見られて嬉しい  
>  (lit.) I was able to see and then (or rather because of it) I'm happy now  
>  I'm glad [that/because] I was able to see [it]

